ERBB2 and breast cancer: Furthermore, molecular biology studies revealed that, compared with HER2‐positive breast cancer, HER2‐low tumors presented significant increases in mutations in genes such as PTEN, GATA3, CBFB, and Akt1, and compared with HER2‐negative cases, HER2‐low tumors presented significantly greater mutation rates in the CBFB, PIK3CA, MAP3K1, and ARID1A genes, particularly in genes related to the PI3K‐Akt signaling pathway [6].