C Control or LAPTM4B‐WT/6RQ‐overexpressing MDA‐MB‐231 cells were transfected with His‐tagged ubiquitin and myc‐tagged Hrs, starved, and stimulated with 100 ng/ml EGF for 30 min before whole‐cell lysate harvest. Total ubiquitinated proteins were purified by Ni‐NTA agarose and analyzed by Western blot.D Quantification of Hrs ubiquitination levels from the Western blot in (C) (mean + SD; n = 5). 