To investigate the expression profile of protein tyrosine kinases (PTKs) in 
normal human epidermal keratinocytes (NHEK) in response to UVA and UVB we 
employed a reversed transcriptase polymerase chain reaction (PCR) approach using 
degenerate primers derived from the conserved catalytic domain of PTKs. 
Quantitative real-time PCR with specific primers was used to confirm the 
influence of UV on the expression of the identified PTKs. Arg (Abelson-related 
gene, Abl2) was the PTK with the highest prevalence (30% of all PTKs) and UVA 
led to a further induction of Arg expression reaching nine-fold mRNA baseline 
expression at 17 h after irradiation. UVB was followed by an initial 
downregulation and a subsequent increase in Arg mRNA reaching five-fold baseline 
levels after 24 h. We conclude that UVA and UVB differentially modify the 
expression of PTKs in NHEK, and that Arg appears to have a major role in the 
response of keratinocytes to UV. These results provide a basis for further 
studies of PTK in UV-induced signaling that regulates protective responses, cell 
growth and carcinogenesis in the skin.