Single-cell transcriptomics and functional assays have illuminated that NRF2-active macrophages commonly reside in hemorrhagic regions of tumors and that the presence of RBC-heme drives the formation of tumor associated macrophages (TAMs) supportive of tumor growth and invasion which have characteristically high NRF2 and HO-1 and low MHC-II [19]. This evidence concerns the gene HMOX1 and neoplasm.