MOB1B is similar to the yeast Mob1 protein. Yeast Mob1 binds Mps1p, a protein kinase essential for spindle pole body duplication and mitotic checkpoint regulation. Three transcript variants encoding different isoforms have been found for this gene. Recombinant human MOB1B protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.