A, GCs were transfected with 500 ng of MKP3-Myc-FLAG plasmid for 6 h as described under “Experimental Procedures.” Following an overnight recovery, GCs were treated without (veh) or with FSH for 1 h and then collected in immunoprecipitation (IP) lysis buffer and sonicated. After removal of the insoluble particles, the soluble fraction was rotated overnight with 20 μg of agarose-conjugated anti-ERK2 (SC 1647 AC) or agarose-conjugated IgG (5). Inputs, bound (IP), and unbound (Flow Through) samples were separated by SDS/PAGE, and the Western blot was probed with the indicated antibody (Ab). The arrow indicates the protein band of interest. The results are representative of two independent experiments. B, soluble lysates were incubated with 20 μg of agarose-conjugated anti-Myc (SC 40-AC) to immunoprecipitate Myc-FLAG-tagged MKP3. For more details, see A. The results are representative of two independent experiments.