In breast cancer, RARRES3 downregulation can lead to tumor cell adhesion involved in metastasis initiation, loss of RARRES3 phospholipase A1/A2 activity can lead to impaired tumor cell differentiation, and RARRES3 has the potential to act as an endogenous inhibitor of immunoproteasome expression (43, 44). The gene discussed is PLAAT4; the disease is breast carcinoma.