PPM1M is a member of the PP2C family of Ser/Thr protein phosphatases. PP2C family members are known to be negative regulators of cell stress response pathways. This phosphatase was identified as an interacting protein of Rho guanine nucleotide exchange factors (PIX). PIX proteins are regulators of p21/Cdc42/Rac1-activated kinase 1 (PAK1), a protein kinase mediating biological effects downstream of Rho GTPases. This phosphatase has been shown to block the effects of PAK, and thus inhibit actin stress fiber breakdown and morphological changes driven by cell division cycle 42 (CDC42).