Stimulation of MCF10A and MCF7 cells with IGF-1 leads to an increase in LIP expression and the LIP/LAP ratio, but not in LIP mRNA expression. A). Western blot analysis of MCF10A cells serum starved for 24 hours prior to 4, or 16 hours of treatment with IGF-1 (2.6 nM) or insulin (10 nM). Whole cell extracts (100 μg) were analyzed via 12% SDS-PAGE and Western blotting using a monoclonal anti-C/EBPβ antibody. β-actin was used to estimate loading and transfer of proteins. The western blot shown is representative of dozens of separate Western blots. The LIP/LAP ratio was quantitated using Li-COR's Odyssey infrared imaging system. LAP1 and LAP2 expression values were combined and normalized to GAPDH. LIP values were also normalized to GAPDH. The fold change in the LIP/LAP ratio from the IGF-1 treated cells vs. the control cells was calculated and statistical significance was determined via an unpaired, 2-tailed T test with a * p value < 0.05. n = 4. B). Western blot analysis of MCF7 cells serum starved for 24 hours prior to 16 hours of treatment with IGF-1 (2.6 nM). The fold change and statistical significance in the LIP/LAP ratio was studied as Figure 1A (n = 5). C-D). MCF10A and MCF7 cells were treated with IGF-1 for 16 hours. Total RNA was extracted and quantitative realtime PCR was conducted with specific C/EBPβ mRNA primers. No obvious difference was observed in C/EBPβ mRNA expression between untreated and IGF-1 treated cells. (MCF10A; n = 3) (MCF 7; n = 6).