By carrying out RNAi and known drug screens on isogenic breast and gastric cell lines with and without E-cadherin, we have identified multiple druggable vulnerabilities in E-cadherin-deficient cells which may be exploited for both the chemoprevention of HDGC and the treatment of sporadic DGC, LCIS, and LBC [8,9]. This evidence concerns the gene CDH1 and lobular breast carcinoma in situ.