PRL induces phosphorylation of the AMPKα subunit at Thr172 and increases levels of phosphorylated ACC at Ser79. Stimulation with 100 ng/ml of PRL increased the levels of A) phosphorylated ACC (pACC) and phosphorylated AMPKα (pAMPKα) in 184B5, MCF-7, and MDA-MB-231 cells as determined by Western blotting. Densitometric analyses revealed significant ~2-fold changes in pACC in MCF-7 and MDA-MB-231 breast cancer cells (p < 0.005 and p < 0.05, respectively), and an increased level of pAMPKα protein in MDA-MB-231 cells (p < 0.02). B) In response to 100 ng/ml of PRL, total LKB1 protein levels were increased by 34 and 23% in MCF-7 and MDA-MB-231 cells, respectively, which was also reflected at the mRNA level. Results represent the mean ± SEM of three independent experiments.