Morphology, growth curve and telomerase activity in PIG-2 -transfected HEK 293 cells. (A) Phase-contrast features of wild-type HEK 293 cells (left panel), cells transfected vector alone (middle panel), and cells transfected with PIG-2 gene (left panel). Magnifications, × 100.(B) Growth stimulatory effect of PIG-2 in HEK 293 cells. PIG-2 induces growth stimulation in 293 cells. Viability of 293 cells after transfection with PIG-2 or pcDNA3.1 vector alone, respectively. The data are the number of viable cells grown for 13 days in culture and represent the mean ± S.D. of triplicate determinations. (C) Determination of telomerase activity. Human telomerase-positive embryonic kidney 293 cells, 293 cell extracts treated with RNase (+ RNase), wild-type 293 cells, cells transfected with vector alone and cells transfected with PIG-2 were analyzed by Telomerase PCR ELISA. Assays were performed according to the kit protocol with amounts of extracts equivalent to 1 × 103 cells. The telomerase activity in 293 cells, which served as a positive control, was abolished by pretreatment with RNase. Results are the average mean absorbance values from three separate experiments (means and 95% confidence intervals).