Fig. 2. Recognition of multiple mitotic phosphoproteins by P190. (A) On western blots, P190 recognizes several phosphoproteins in nocodazole-arrested cells (lane 2) but not in unsynchronized (lane 1) or thymidine-treated (lane 3) cells. Molecular weight markers are shown in kD. (B) P190 recognizes a subset of mitotic phosphoproteins that are distinct from those recognized by MPM-2 and CC3 and that show differential sensitivity to CDK inhibition and phosphatase treatments. Shown are western blots on lysates from cells treated with nocodazole (N), roscovitine (R) or alkaline phosphatase (AP), as indicated, and probed with P190, MPM-2 or CC3 antibodies. (C) Strategy for identifying protein complexes and phosphorylation sites containing the P190 phosphoepitope. (D) Immunoprecipitation with P190 (lanes 1 and 3) or control antibody (lanes 2 and 4) eluted with 8 M urea (lanes 1 and 2) or boiling in SDS gel loading buffer (lanes 3 and 4).