The B regulatory subunit might modulate substrate selectivity and catalytic activity, and might also direct the localization of the catalytic enzyme to a particular subcellular compartment. Within the PP2A holoenzyme complex, isoform 2 is required to promote proapoptotic activity (By similarity). Isoform 2 regulates neuronal survival through the mitochondrial fission and fusion balance (By similarity). . This is the function of PPP2R2B (protein phosphatase 2 regulatory subunit Bbeta, ENSG00000156475).