CPT1A mRNA and protein levels are elevated in breast cancer cells and increase in response to PRL. Basal mRNA levels were determined by real time PCR, revealing that A) CPT1A expression was elevated in both MCF-7 and MDA-MB-231 cells by 5.1 and 7.3 fold, respectively (p < 0.0001), relative to 184B5 cells, while B) FASN mRNA levels were over 6-fold lower in both breast cancer cell lines relative to 184B5 cells (p < 0.0001). C) A 100 ng/ml dose of PRL significantly increased CPT1A mRNA levels by 1.8- and 1.6-fold in MCF-7 and MDA-MB-231 breast cancer cells, respectively (p < 0.001) relative to untreated cells. In A), B), and C), different letters represent statistical differences between groups. D) A representative Western blot depicting the 86 kDa CPT1A protein (top). Densitometric analysis (bottom) revealed that 100 ng/ml of PRL increased protein levels by 61 and 45% in MCF-7 and MDA-MB-231 cells, respectively. All results represent the mean ± SEM of three independent experiments.