Functions as an activator subunit for the CBK1 protein kinase. Part of the regulation of ACE2 activity and cellular morphogenesis (RAM) signaling network. Required for coordinating polarized cell growth during interphase with the onset of mitosis. Required for mother/daughter cell separation after cytokinesis. Also has a role in the prevention of nuclear export of ACE2 from the daughter cell nucleus after mitotic exit. It coordinates ACE2-dependent transcription with mitotic exit network activation. Interacts with protein kinase CBK1 to form the RAM CBK1-MOB2 kinase complex. Localizes to the bud cortex during polarized growth and to the bud neck and daughter cell nucleus during late mitosis. Present with 2250 molecules/cell in log phase SD medium. Belongs to the MOB1/phocein family.