Thirty-eight of these 39 unique genes were over-expressed in ERα-positive breast tumors with PIK3CA mutations, 16 being up-regulated at least 3-fold, while only one gene (NKAIN1, encoding Na+/K+ ATPase interacting protein) was down-regulated, with a FC of 3.52. The gene discussed is NKAIN1; the disease is breast neoplasm.