Figure 4.

.  Characterization of K-370 antibodies against mouse and human telomerase catalytic subunits. Western blot analysis of total cell lysates from the indicated mouse (MEF, FM3A) or human (IMR-90, 293) cells using K-370 antibodies in the absence of competing peptides, or in the presence of the antigenic peptide PEPT-1 or the unrelated peptide PEPT-2. FM3A is a mouse immortal cell line; IMR-90 cells are nonimmortalized human diploid fibroblasts; and 293 cells are adenovirus-transformed human fibroblasts. MEFs had undetectable mTERT protein in this assay and IMR-90 cells are negative for telomerase activity, whereas FM3A, MEFs, and 293 have detectable telomerase activity.