To further test the correlation between ERRF expression and lapatinib sensitivity, we analyzed ERRF expression and sensitivities of breast cancer cell lines to ERBB2 drugs including lapatinib in a published study [45] and the CCLE, and found that lapatinib sensitive cell lines expressed significantly higher levels of ERRF than lapatinib resistant cell lines (Figure 1E). This evidence concerns the gene SRARP and breast carcinoma.