Figure 1

Schematic representation of signalling events triggered in skin cells upon exposure to UV radiation. The two compartments in the image represent the two cell types- keratinocyte and melanocyte. Generic proteins are represented in rectangular boxes while receptors are specifically shown on the membrane; biological processes are represented as hexagons, and secondary messengers and other small molecules involved in the signaling network as ellipses and circles. The environmental triggers UVA and UVB are represented as pink ellipses. Complexes of two or more proteins are also depicted in rectangles, with the proteins involved in the complex separated by a colon (:). The arrows describe the nature of interaction: activation is depicted as , inhibition as , expression as and third molecule regulation as . The schema also describes paracrine (reactions occurring within a compartment) and autocrine (reactions occurring cross-compartmentally) signalling.