To further verify the bioinformatics data shown above, we tested the gene expression level of IDH2 among different breast cancer molecular typing cell lines in vitro, including MCF-10A (normal human mammary epithelial cells), MB-231 (TNBC subtype cells), MCF-7 (luminal subtype cells), and AU565 (Her2+ subtype cells). The gene discussed is ERBB2; the disease is breast cancer.