Fig. 1. Induction of expression of EGFR ligand mRNA, by scraping, in human and mouse keratinocytes. Confluent NHEK (A) and normal mouse epidermal keratinocytes (B) were scraped with a pipette tip; total RNA was harvested at several time points and mRNA expression was analyzed by RT-PCR. Right panels show densitometric analysis. In both cell types HB-EGF mRNA was rapidly and dramatically induced after scraping, whereas TGF-, AR, and EPR mRNA were slightly induced in NHEK and the normal keratinocytes, although in the latter cells EPR was also increased.