Table 1.

The classification and functions of the regulatory factors involved in macropinocytosis process.

Regulatory factors		The relevant function
Rho GTPases	Rho : RhoA,RhoC,RhoG	Being activated and playing a role in the formation of macropinosomes.
	Cdc42	Combing with GTP to activate PAK1 to regulate actin in the cytoskeleton.
	Rac: Rac1	The sequential activation of Rac1 followed by inactivation promoting the formation of macropinosomes.
Ras GTPases	Ras	Ras activation stimulates the formation of macropinosomes, and the peak of Ras activity occurs after the formation of macropinosomes.
Arf GTPases	Arf1	Regulating actin cytoskeleton remodeling.
	Arf6	The presence of Arf6 has a guiding effect on the location of activated Rac1 on the plasma membrane.
Rab GTPases	Rab5	Regulating the actin skeleton remodeling and stabilizing macropinosomes and is one of the markers of early macropinosomes.
	Rab7	One of the markers of late macropinospmes.
	Rab20, Rab21	They function at the maturity stage of macropinosomes.
	Rab34	Promoting the formation of membrane ruffles.
PI	PI(4,5)P2	Binding to a variety of actin, activating actin, regulating actin polymerization, and promoting the shrinkage of the plasma membrane.
	PI(3,4,5)P3, PI(3,4)P2	Binding with Akt, Btk, PDK1, ARNO, and other proteins to activate downstream signaling pathways and regulating the depolymerization and reconstruction of actin.
	PI(3)P	Localizing on the macroponosomes membrane and the tubule membrane extending from macroponosomes and controlling early endosomes.
	PI(3,5)P2	Control late endolysosomes.