Figure 5. HER2 overexpression prevents prolactin-induced activation of the FASN gene promoter. Estradiol-depleted MCF-7/neo and MCF-7/Her2-18 cells were transiently transfected with a plasmid containing a luciferase gene driven by a 178-bp FASN gene promoter fragment harboring a SREBP-binding site, flanked by auxiliary NF-Y and Sp-1 sites or with a similar construct in which the SREBP domain was deleted. The next day, cells were treated with recombinant prolactin (PRL) in the presence or absence of hPRL-G129R in 0.5% CCS. After ~24 h of incubation, cells were lysed, luciferase activity was measured and relative (fold) changes in transcriptional activities of FASN promoter-luciferase-transfected cells were calculated. The data are shown as the means (columns) ± S.D. (bars) from three separate experiments (performed in duplicate). Luciferase activity in PRL- and/or G129R-treated cells was compared with that in vehicle-treated control cells (* P < 0.05; ** P < 0.005).