Detection of telomerase activity of the 8 TERC mutations through TRAP analysis. Detection of telomerase activity is shown in vitro (A) and in vivo (B). The arrows denote the start of the TRAP ladder (TRAP), the corresponding internal control (IC), the amount of activity in relationship to WT TRAP levels (%), and the control of the assay where an equal amount of RNA was loaded (RNA) or the levels of luciferase was measured (Luc) to control for the corresponding TRAP experiment. The mutations are shown above the panels. Serial dilutions of each lysate were assayed as described in “Materials and methods.” The percentage figures shown for the TRAP activities are approximate values derived from comparing TRAP ladders from serial dilutions from mutant samples with those from WT samples.