Of note, Bentz et al. protein TKTL1 in malignancy cells has been reported to correlate with enhanced glycolysis and lactic acid production. Furthermore, enhanced TKTL1 expression was put into context with resistance to chemotherapy and ionizing radiation. Here, a panel of human malign and benign cells, which cover a broad range of chemotherapy and radiation resistance as well as reliance on glucose metabolism, was analyzed for TKTL1 expression. Methods 17 malign and three benign cell lines were characterized according to their expression of TKTL1 around the protein level with three commercially available anti-TKTL1 antibodies utilizing immunohistochemistry and Western blot, as well as on mRNA level with three published primer pairs for RT-qPCR. Furthermore, sensitivities to paclitaxel, cisplatin and ionizing radiation were assessed in cell survival assays. Glucose consumption and lactate production were quantified as surrogates for the Warburg effect. Results Considerable amounts of tktl1 mRNA and TKTL1 protein were detected only upon stable transfection of the human embryonic kidney cell collection HEK293 with an expression plasmid for human TKTL1. Beyond that, poor expression of endogenous tktl1 mRNA was measured in the cell lines JAR and U251. Western blot analysis of JAR and U251 cells did not detect TKTL1 at the expected size of 65?kDa with all three antibodies specific for TKTL1 protein and immunohistochemical staining was observed with antibody JFC12T10 only. All other cell lines tested here revealed expression of tktl1 mRNA below detection Puerarin (Kakonein) limits and were unfavorable for TKTL1 protein. However, in all cell Puerarin (Kakonein) lines including TKTL1-unfavorable HEK293-control cells, antibody JFC12T10 detected multiple proteins with different molecular weights. Importantly, JAR and U251 did neither demonstrate an outstanding production of lactic acid nor increased resistance against chemotherapeutics or to ionizing ANGPT2 radiation, respectively. Conclusion Using RT-qPCR and three different antibodies we observed only exceptional occurrence of TKTL1 in a panel of malignant human cell lines Cells were cultured in 75?ml culture flasks (Biochrom, Berlin, Germany) as monolayers and harvested at 80-90% confluence using a cell-scraper (Biochrom) for further experiments. HEK293 cell transfectants stably generating full-length TKTL1 protein (293pCAG TKTL1) were used as positive control cells. HEK293 cells transfected with vacant expression vector (293pCAG ) do not produce TKTL1 protein and were used as unfavorable control cells. Both transfectants have been previously explained in detail [21]. For the present study the transfectants were named as follows: 293pCAG TKTL1?=?HEK293-TKTL1 transfectants and 293pCAG ?=?HEK293-control transfectants. Table 1 Cell lines and main cells mRNA expression by quantitative RT-PCR (RT-qPCR) Quantitative RT-PCR (RT-qPCR) was performed with three different primer pairs specific for the three mRNA splice variants available in GenBank (PubMed) and published previously [7, 28, 35]. Results of RT-qPCR for all those cell lines investigated are shown in Table?4, while Table?5 summarizes basic quantitative PCR data for all those three primer pairs. For this, HEK293-TKTL1 transfectants, HEK293 control transfectants and JAR and U251 cells were analyzed. JAR and U251 were recognized to weakly express endogenous tktl1 mRNA with all three primer pairs (Table?4). Primer pair 1 (located in the non-coding region of TKTL1 gene) did not identify coding TKTL1 mRNA in HEK293-TKTL1 transfectants, whereas primer pairs 2 and 3 did. In comparison to JAR and U251 cells, the large quantity of tktl1 mRNA in the other malign and benign cells was comparable to or below levels of the TKTL1-unfavorable HEK293 control cell lines, and thus defined as unfavorable Puerarin (Kakonein) (Table?4). The relative expression levels of tktl1 in JAR and U251 were increased up to 560-fold in comparison to the other cells (example for primer pair 3 and JAR and MDA-MB 231). Table 4 Relative normalized quantification of TKTL1 gene expression with the three published primer pairs TKTL1(1), TKTL1(2) and TKTL1(3) were determined as explained in material and methods and are shown for 21% oxygen. Glucose Puerarin (Kakonein) consumption and.