PIK3CA and breast cancer: Up-regulation was also confirmed for genes related to breast cancer (MAPT, HMGCS2, NR2F2 and TFAP2B), genes involved in metal ion binding (CYP4Z1, CYP4Z2P, SLC40A1, LTF and LIMCH1) and also NRIP3, NTN4, REEP1, SEC14L2 and TMC5. Deregulation of these genes was not related to ERα status or proliferation since similar expression levels of ERα and MKI67 were observed in PIK3CA-mutated and -non mutated tumors (Table 4).