||Ankyrins are membrane adaptor molecules that play important roles in coupling integral membrane proteins to the spectrin-based cytoskeleton network. Mutations of ankyrin genes lead to severe genetic diseases, such as fatal cardiac arrhythmias and hereditary spherocytosis. ANKRD30A (ankyrin repeat domain 30A， also known as serologically defined breast cancer antigen NY-BR-1, is a 1,397 amino acid coiled-coil protein. Containing six ANK repeats and thirty-seven exons, ANKRD30A is a distant homolog of the POTE family. Initiated by either Dnmt1 or Met-57, ANKRD30A is highly expressed in breast and testis, and faintly in placenta. Present in 80% of breast cancers, but not in other types of tumors, ANKRD30A is a differentiation antigen and a potential target for antibody‐based therapies in breast cancers.