E Endogenous LAPTM4B is targeted to both early and late endosomes. MDA‐MB‐231 cells were fixed and costained for endogenous LAPTM4B (red) and EEA1 or LAMP1 (green). Boxes are selected regions for magnified view. Note: non‐specific nuclear staining by the LAPTM4B anti‐sera. Scale bar: 10 μm.F Quantification of LAPTM4B colocalization with EEA1 and LAMP1 (mean + SD; n ≥ 4). 