JIP4 preferentially localizes to PtdIns3P-positive tubules from macropinosomes. Shown is a macropinocytosing RPE1 cell with mNeonGreen-JIP4 (pseudocolored green) and Halo-2xFYVE(WDFY2) as a probe for PtdIns3P (pseudocolored magenta). Macropinosomes acquire both JIP4 and PtdIns3P, and JIP4 concentrates where PtdIns3P-positive tubules emerge and shortly thereafter.