MDA‐MB‐231 cells were transfected with GFP‐Rab5Q79L and Flag‐LAPTM4B, starved, and stimulated with Alexa‐555‐EGF for 90 min and followed by intraluminal sorting analysis. See Materials and Methods for details. Quantification of EGF localization in LAPTM4B‐positive and LAPTM4B‐negative endosomes in (E) (mean + SD; n = 3; ***P 0.0007, one‐tailed t‐test). 