MTT proliferation assay and analysis of apoptosis in ribozyme-transfected NB4-R1 cells. (A) Cells transfected with either the control ribozyme, APL 5.0, or the catalytic ribozyme, APL 1.1, were cultured in 65 or 195 μg/mL hygromycin in the absence (−) or presence (+) of 10−6 mol/L ATRA for 5 days. The MTT assay was performed on days 3 through 6 (X axis). The Y axis depicts the optical density (O.D.). These data are from one experiment representative of four independent analyses. (B) Untransfected NB4-R1 cells and cells transfected with either the control ribozyme, APL 5.0, or the catalytic ribozyme, APL 1.1, were cultured without hygromycin (0 μg/mL) or with 65 or 195 μg/mL hygromycin (hygro) in the absence (−) or presence (+) of 10−6 mol/L ATRA for 4 days. The Tdt assay was used to assses induction of apoptosis (▧) on day 4. Viability was concurrently measured using trypan blue dye exclusion (⧫). These data are from one experiment representative of four independent analyses.
