In addition to KS, HO-1 is highly induced in several other cancers, where it has been shown to contribute to tumor progression by promoting cell proliferation, angiogenesis, cytoprotection, and resistance to chemotherapy (Ryter and Tyrrell, 2000; Ryter et al., 2006; Lanceta et al., 2015). This evidence concerns the gene HMOX1 and Kaposi's sarcoma.