Figure 7.

Interaction between cohesin and splicing factors is enhanced in mitosis. A, top, HeLa cells were synchronized by double thymidine block and whole-cell protein lysates (1% Nonidet P-40) prepared at different time points following release. Endogenous cohesin complexes were then immunoprecipitated with SMC1A antibodies or IgG control antibodies, and Western blotting with the antibodies indicated was performed. Bottom, direct Western blotting of the lysates studied at the top, demonstrating that the amount of cohesin and splicing factor proteins in the lysates does not change over the course of the cell cycle and demonstrating the efficiency of synchronization using cell cycle stage–specific antibodies (S phase, cyclin E1; G2, cyclin B1; M, phospho-H3). B, interaction between cohesin and splicing factors is enhanced in mitosis. Proliferating HeLa cells were treated with DMSO (AS), hydroxyurea (S), RO-3306 (G2), and nocodazole (M) for 24 h. Protein lysates were prepared (1% Nonidet P-40), subjected to immunoprecipitation (IP) with SMC1A antibodies, and studied by Western blotting with the antibodies indicated.