LAPTM4B  Lysosomal-associated transmembrane protein 4B is a protein that in humans is encoded by the "LAPTM4B" gene. LAPTM4B protein contains a lysosome localization motif and localizes on late endosomes and lysosomes. Increased expression of LAPTM4B has been found in breast, liver, lung, ovarian, uterine, gastric cancers. Elevated LAPTM4B level contributes to chemotherapy resistance in breast cancer. It was found that overexpression of LAPTM4B causes anthracyclines (doxorubicin, daunorubicin, and epirubicin) resistance by retaining drug in the cytoplasm and decreasing nuclear localization of drug and drug induced DNA damage. In 2011, the same group reported that LAPTM4B also promotes autophagy, a cell survival mechanism mediated by lysosomes. LAPTM4B promotes autophagy and renders tumor cells resistant to metabolic and genotoxic stress and results in more rapid tumor growth. Based on these findings, LAPTM4B can be utilized to be a therapeutic target to prevent chemotherapy resistance or a marker to identify the patients who will not benefit from anthracyclines.