Howell et al.105discovered that PRLR antagonist Δ1–9‐G129R‐hPrl hinders the activation of PRLR, which promotes the apoptosis of ER+ and ER− breast cancer cells, increases the cytotoxic effect of doxorubicin and paclitaxel in vitro. The gene discussed is ESR1; the disease is breast carcinoma.