ABCG2 and breast cancer: Another very recent study in estrogen receptor negative breast cancer cells and in patient-derived nude mice xenografts treated with docetaxel, shRNA mediated silencing of GHR indeed suppressed multi-drug efflux pump ABCG2 and re-sensitized the tumors to the anti-cancer agent[149], thereby providing additional evidence to GHR-mediated induction of drug efflux via upregulated ABC-transporter expression.