The intracellular degradation of a subset of proteins is a functional consequence of protein post-translational modifications, including phosphorylation and ubiquitylation.42, 43 The 26 S proteasome- and the lysosome-dependent proteolytic pathways are known to govern intracellular protein turnover.42 To determine whether either one or both of these pathways are involved in the regulation of FOXO3A and FOXO4 protein turnover in RAS-mutant cancer cells, we incubated HCT-116 and SW480 cells with the proteasome inhibitor MG132 or the lysosome/autolysosome inhibitor Bafilomycin A (Baf A). The gene discussed is FOXO3; the disease is cancer.