PRL and breast cancer: The levels of total LKB1 protein were modestly but significantly increased by 34 and 23% following stimulation with PRL in both MCF-7 and MDA-MB-231 breast cancer cells, respectively (Figure 3B; 1-fold vs. 1.34 ± 0.04-fold, p < 0.0001, and 1 vs. 1.23 ± 0.03-fold, p = 0.0002, respectively).