Regulatory subunit of serine/threonine-protein phosphatase 4. May regulate the activity of PPP4C at centrosomal microtubule organizing centers. The PPP4C-PPP4R2-PPP4R3A PP4 complex specifically dephosphorylates H2AX phosphorylated on 'Ser-140' (gamma-H2AX) generated during DNA replication and required for DNA DSB repair. Serine/threonine-protein phosphatase 4 (PP4) occurs in different assemblies of the catalytic and one or more regulatory subunits. Component of the PP4 complex PPP4C-PPP4R2-PPP4R3A. Interacts with PPP4C; the interaction requires PPP4R2. In interphase localized in the cytoplasm and in the nucleus (with higher levels). During metaphase located in pericentriolar regions. Belongs to the SMEK family. Wrong choice of frame. Truncated N-terminus. Probable intron retention. Truncated N-terminus. Extended N-terminus.