Expression of AP-2 family members in HC11 cells. RNA from HC11 cells cultivated in EGF-containing medium (EGF) or in differentiation conditions (DIP) was subjected to RT-PCR using primers specific for the AP-2 isoforms indicated (upper panel) or milk protein genes (middle panel). Amplification of beta-actin served as a loading control (lower panel). Control reactions were carried out in the absence of reverse transcriptase (-RT). Positive controls (contr.) consisted of cloned PCR fragments (10 pg plasmid DNA) in the case of AP-2 isoforms, or of cDNA derived from a lactating mouse mammary gland for differentiation markers.