Cytosolic MOB1A and MOB1B are phosphorylated by phospho-STK4 (p-MST1). Phosphorylated (active) STK4 (p-MST1) and SAV1 are known to form a complex and that complex is annotated as the catalyst of this reaction. Threonine residues 12 and 35 have been experimentally identifed as the targets of MOB1A phosphorylation; the homologous residues of MOB1B are inferred likewise to be targets (Praskova et al. 2008).
