Importin-β interacts with RANBP2 in normal and MT-lacking mitotic cells. (A) Protocol for protein extract preparation from cultures reaching mitosis after thymidine release (a) or in the presence of nocodazole (NOC) to prevent MT polymerization (b). Bar, 10 µm. Protein extracts were prepared immediately after cell harvesting. (B) WB analysis of coIP proteins using anti–importin-β or nonspecific IgG for control. (C) Reciprocal analysis of proteins in the RANBP2 coIP and in cell extracts incubated with nonspecific IgG.