ERBB2 and breast cancer: The SGSM2 mRNA level correlated with ER+, PR+, and HER2 – BC (***P < 0.001; Supplementary Table 1), and increased SGSM2 mRNA expression was predominately detected in tissue samples from patients with luminal A type BC compared with HER2-enriched and basal-like BC patients (Scheffe test, ***P < 0.001).