N4BP1 and breast cancer: However, considering that FAM189A1 and FAM189B, as well as NDFIP1, NDFIP2, and N4BP1, are infrequently downregulated in cancers (Figs EV1 and EV4A), we concluded that ENTREP/FAM189A2 encodes a unique member of a new class of ITCH activator proteins that are downregulated in various cancers, such as breast cancer.