Lan Y, et al. - Since the molecular mechanisms through which fibroblasts sense ultraviolet radiation (mainly UVA) and trigger the cell signalling pathways involved in the upregulation of MMPs were not well elucidated, researchers studied the function and potential mechanisms of photoageing of opsin (OPN)3 in normal human dermal fibroblasts (NHDFs). Findings suggested that OPN3 initiates UVA phototransduction in NHDFs. The study shows the expression of OPN on human dermal fibroblast membranes for the first time. OPN3 relies on the calcium pathway to trigger and upregulate MMP expression in response to UVA irradiation and thus acts as a photoreceptor which plays an important role in skin photoageing.