While the anti-tumor effects of the flaxseed lignan SDG have been thoroughly established in several models of ERα-positive breast cancer [9–12, 14–17, 35], less attention has been given to its impact on ERα-negative models, including models of basal-like and other triple-negative breast cancer subtypes, and the precise mechanisms mediating their effects. The gene discussed is ESR1; the disease is breast carcinoma.