Telomerase enzymatic activity in VA13+hTERT cells simultaneously expressing various hTERC variants and the wild-type copy from a single pBud-CE 4.1 vector series. (A) While the wild-type hTERC copies are expressed from both the cellular EF1α and the viral CVM promoters, the mutated hTERC genes (ie, either the G305A or the G322A) are alternatively expressed from either the EF1α or the CMV promoter with respect to the wild-type hTERC copy. Serial 5-fold dilutions of the transfected cell lysates (indicated by triangles) were assayed for each sample to ensure linearity of the assay. (−) Telomerase function of an aliquot of the sample that expressed both wild-type copies was inactivated by denaturing the sample at 95°C for 3 minutes prior to assaying for telomerase enzymatic activity. (+) indicates PCR products amplified from the control TSR8 template supplied in the kit. Panels B, C, and D show telomerase activities of the wild-type hTERC gene expressed from the EF1α promoter in the same lysates that contained the individual hTERC variants expressed from the CMV promoter. “IC” indicates PCR products amplified from an internal control DNA template, which is used as internal control for PCR amplification efficiency in each reaction.