ESR1 and neoplasm: To test our hypothesis that extranuclear ERα participates in E2-induced T47D:A18/PKCα tumor regression, we asked whether ERα localization differs in E2 and RAL-induced T47D:A18/PKCα regressing tumors compared with TAM-stimulated T47D:A18/PKCα tumors or E2-stimulated T47D:A18/neo tumors.