The interaction of UVA and UVB wavebands with particular emphasis on signalling.

The molecular response mechanisms and signalling pathways activated upon exposure to ultraviolet (UV) radiation have been extensively studied within the last two decades. Although many signalling pathways can be activated by both UVA as well as UVB, there are several distinctions indicating wavelength-specific response patterns accommodated by the terms UVA response and UVB response. Given that human skin is primarily exposed to UV light from solar radiation consisting of both UVA and UVB, we sought to explore a potential interaction between the distinct UVA and UVB responses at the level of MAPK. Our results indicate that the two distinct stress responses elicited by UVA or UVB interact with each other, producing a "third" response that is different from either alone and cannot be explained by a simple addition of effects.