Reducing C/EBPδ expression inhibits HC11 mammary epithelial cell differentiation. HC11 nontransfected control cells, HC11 stably transfected vector (pSilencer™ 2.1 neo) control ("vector") cells and HC11 C/EBPδ siRNA treated cells were grown to confluence in CGM. Cells were cultured in CGM without lactogenic hormones (-) or in CGM plus lactogenic hormones (+) for 4 days. Total cellular RNA was isolated and Northern blot analysis performed. Northern blots were probed with 32P-labelled C/EBPδ and β-casein expression cDNA probes. CP was used as the loading control. Results presented are for mRNA levels from duplicate samples analyzed in this experiment. The results presented are representative of 3 experiments.