To examine whether SMYD3‐mediated methylation influences the phosphorylation status of HER2 protein, we knocked down SMYD3 in breast cancer cell lines using specific siRNAs and compared autophosphorylation levels of HER2 at Tyr 1248 that was indicated to be essential for HER2 activity 28. This evidence concerns the gene ERBB2 and breast carcinoma.