GPNMB is a type-I transmembrane protein that is expressed not only in cancer cells, but also in many normal cells, including KCs (27), MCs (28, 29), macrophages (30, 31), dendritic cells (32, 33), osteoblasts (34, 35), microglia (36, 37), and neurons (38, 39). The gene discussed is GPNMB; the disease is cancer.