GPNMB and neoplasm: Unlike its role in maintaining homeostasis in non-tumor diseases, GPNMB mediates immune suppression by promoting the polarization of tumor-associated macrophages toward the M2 phenotype and metastatic colonization by enhancing tumor cell metabolism and invasive capacity through aberrant activation of common pathways such as CD44/NF-κB and mTORC1 in tumors (Lazaratos et al., 2022).