Regulatory subunit of serine/threonine-protein phosphatase 4 (PP4) (By similarity). The probable PP4 complex Pp4-19C-PPP4R2r-flfl (PPP4C-PPP4R2-PPP4R3) is required to prevent caspase induced cell death (in vitro). Serine/threonine-protein phosphatase 4 (PP4) occurs in different assemblies of the catalytic and one or more regulatory subunits. Probably part of a PP4 PPP4C-PPP4R2-PPP4R3 complex containing Pp4-19C, PPP4R2r and flfl. Belongs to the PPP4R2 family.