Figure 7.

Macropinocytosis and phagocytosis are biochemically distinct processes. Phagocytosis and macropinocytosis are actin-driven processes that both require Rab7, myosin I's, and coronin. Phosphatidylinositol 4,5-bisphosphate also appears to play an important role in both processes. The model proposes that PI 3-kinase generates PI (3,4,5)P₃, which together with profilin and LIMP regulates macropinocytosis. The activity of PLC generates diacylglycerol (DAG) and inositide trisphosphate (IP₃) in combination with the GTPases Rap1 and RacC to regulate phagocytosis. In addition, published data support a negative role for Rap1 and RacC in macropinocytosis.