Energy-dependent efflux transporter responsible for decreased drug accumulation in multidrug-resistant cells (PubMed:12960149, PubMed:22306008, PubMed:15899824, PubMed:15205344). Specifically present in limbal stem cells, where it plays a key role in corneal development and repair (By similarity). ATP + daunorubicin(in) + H2O = ADP + daunorubicin(out) + H(+) + phosphate Expressed by CD133-expressing progenitor cells among epidermal melanocytes (at protein level). Widely expressed with specific expression in pigment cells. Highly expressed in several malignant tissues: highly expressed in clinical melanomas, with low expression in normal skin. In melanoma, marks malignant melanoma-initiating cells (MMIC), in which clinical virulence resides as a consequence of unlimited self-renewal capacity, resulting in inexorable tumor progression and metastasis. Also highly expressed in a number of leukemia cells. Expressed in basal limbal epithelium. Acts as a marker of stem-like cells (CSC) in a number of malignancies (PubMed:24934811). Associated with clinical drug resistance, tumor progression and disease recurrence in malignant melanoma and acute leukemias. Responsible for the resistance to doxorubicin of a subset of malignant melanomas. ABCB5-expressing cells selectively survive when exposed to dacarbazine drug, the reference treatment of metastatic melanoma, vemurafenib and other various chemotherapeutic drugs, suggesting that anti-melanoma chemotherapy participates in the chemoresistance acquisition by selecting tumor cell subpopulations expressing ABCB5 (PubMed:22784549, PubMed:22044138, PubMed:22675422, PubMed:23770371, PubMed:24934811). Present in melanoma-initiating cells that acts as an enhancer of tumor growth by promoting CSC maintenance and tumor growth by controlling IL-1beta (IL1B) secretion to maintain slow-cycling, chemoresistant cells through an IL-1beta (IL1B)/IL8/CXCR1 cytokine signaling circuit (PubMed:24934811). Belongs to the ABC transporter superfamily. ABCB family. Multidrug resistance exporter (TC 3.A.1.201) subfamily. Was named ABCB1 by some authors. Truncated N-terminus. Extended N-terminus.