Figure 5.
Effects of dominant-negative TERT mutants on 293 cells with short telomeres. (A) Western analysis of 293 mutant clones B12 and C4. Cells were grown in the presence or absence of muristerone and passed every 3 days for a total of nine passages. (arrowhead) Expression of mutant TERTs. Mouse Anti-FLAG monoclonal antibody was used. (B) TRAP assay of B12 and C4 at each passage as in A. (Lanes 1–5) The serial dilution of 293 lysate. One microgram from each lysate was assayed. (C) Comparison of growth of B12 and C4 in the presence and absence of muristerone. Cells were grown, passed, and counted as in A. Data represent population doublings in each passage. (Left) (□) 293B12 (−); (♦) 293B12 (+). (Right) (□) 293C4 (−); (♦) 293C4 (+). (D) Colony formation assay of EcR-293, clone B12, and clone C4 as described in Materials and Methods. (−) Uninduced; (+) induced.