FIG. 3.
Comparison of p90rsk-rat-1 and p90rsk-rat-Δ kinase activities. Cos-7 cells were transiently transfected with pMT2 vector control (V), pMT2-rskrat-1 (rsk), pMT2p85.epi (HA-rsk), or pMT2-rskrat-Δ (HA-rsk-Δ) as described in Materials and Methods. Cells were stimulated for 5 min with EGF (hatched bars) or with carrier BSA (solid bars) and harvested by sonication in buffer H. Sixty micrograms of the cell extracts obtained by centrifugation at 100,000 × g was immunoprecipitated with anti-HA antibody. After two washes, the immunoprecipitates were assayed for S6 kinase activity as described in Materials and Methods.