Fig. 6. Growth advantage conferred on MEFs by the loss of one copy of sno. (A) Growth curves of MEFs. The average and standard deviation of triplicate measurements are shown for each time point. (B) Cell cycle analysis. Exponentially growing MEFs were stained with propidium iodide and analyzed by FACScan. The average population and standard deviation of triplicate measurements are shown. (C) Expression of cdc25A. Poly(A)⁺ RNA was isolated from confluent MEFs and expression of cdc25A and GAPDH was analyzed by Northern blotting. The amount of cdc25A mRNA was normalized with respect to the GAPDH mRNA level, and the relative amount is indicated as a bar graph. (D) Analysis of apoptosis of MEFs. Apoptosis was induced and cells were assayed at the indicated time points. TNF-α (10 ng/ml) and cycloheximide (5 µg/ml); sorbitol (0.4 M); UV irradiation (390 J/m²); etoposide (100 µM). The average and standard deviation of triplicate measurements are shown for each time point.