For example, in the slime mold Dictyostelium discoideum, PP4 phosphatase activity is necessary for chemotaxis, and in human colorectal carcinoma cells, active PP4 promotes cell migration.25, 30 PP4 is also a positive regulator of Rac1-dependent cell movement in cultured HEK293 cells.30, 31 The role of the PP4 complex in glial responses to neural injury, however, has never been explored. The gene discussed is PPP4C; the disease is colorectal carcinoma.