Fig. 2. Specific expression of p90Rsk isoforms during mouse spermatogenesis. (A) Northern blot analysis of total RNA (20 µg) isolated from total testis or purified cell populations (see Materials and Methods) with specific cDNA probes for p90Rsk1, p90Rsk2 and p90Rsk3. (B) Western blot analysis of p90Rsk isoforms as in A confirms the results obtained with mRNAs analysis at the protein level. Immunoprecipitation of soluble protein extracts (500 µg) obtained from same cell populations as in A was performed using antibodies specific to p90Rsk1, p90Rsk2 or p90Rsk3, and immunoprecipitated proteins were analyzed by western blot using the same specific antibodies. As positive control, immunoprecipitated proteins obtained from COS cells transfected with recombinant p90Rsk1, p90Rsk2 or p90Rsk3 were used as control for antibody specificity. Molecular weights were calculated using the Gibco Benchmark protein ladder as standard.
