Additionally, the BT474.Br cells (derived from BT474-m1, intracarotid transplantation) [105,106,107], SKBRM cells [108,109], JIMT-1-BR3, SUM-190-BR3 cells (intracardiac injection) [110,111,112], MDA-MB-361-BR2/BR3 cells (intracardiac injection) [113] and HCC1954-BrM1 cells [93] are often used for the study of brain metastasis in HER2-positive breast cancer. The gene discussed is ERBB2; the disease is breast carcinoma.