In vitro telomerase activity of the TERC RNA and TERT variants in WI-38 VA-13 cells. WI-38 VA-13 cells were transfected with a plasmid expressing the mutant or WT TERT cDNA sequences and a plasmid expressing the respective WT or mutant or TERC RNA. Telomerase activity was determined using a quantitative PCR-based TRAP assay. Activity is shown in comparison to the activity obtained after transfection with WT (= 1.0). Values above each column are the average of triplicate experiments. Error bars represent SD, * indicates the difference between the variant, and WT is statistically significant at the level of .05. In vitro telomerase activities of the TERT mutants H412Y, P704S, Y846C, and H876Q have been reported previously.³²