By contrast, eriocalyxin B (Figure 4E) inhibits STAT3 through a covalent binding to Cys712, that is closed to the SH2 domain of STAT3, as evidenced using LC-MS/MS, in order to block STAT3 phosphorylation and cell apoptosis of lung and breast cancer cells [157]. This evidence concerns the gene STAT3 and breast carcinoma.