BLTP2 is recruited to macropinosomes undergoing fusion with the PM in COS-7 cells. (A) Acute recruitment of BLTP2^EGFP to macropinosomes (labeled by internalized fluorescent anti–MHC-I antibodies) in the process of fusing with the PM. (B) Z-stack of the time-lapse images shown in Fig. 7 A, proving that the macropinosome is not moving out from the focal plane during the imaging session. (C) Recycling macropinosomes that acquire BLTP2 signal remain positive for PHAKT and do not transition to the APPL1 stage. (D) BLTP2-positive recycling macropinosomes are not positive for Rab5. (E) BLTP2-positive recycling macropinosomes are positive for the Rab8A, an exocytic Rab. (F) Upon treatment of cells with the VPS34 inhibitor SAR405, the PI3P-positive early macropinosomes can reacquire PI(4,5)P2 and recycle back to the PM.