Analysis of BC expression in gefitinib‐resistant PC9G cells and gefitinib‐sensitive PC9 cells, in the public microarray dataset GSE34228,29 showed that BC expression was increased in the gefitinib‐resistant cells (PC9GR) compared with that in the gefitinib‐sensitive cells PC9 after EGF treatment (Figure 2B). This evidence concerns the gene EGF and breast cancer.