UVB-induced skin aging is primarily caused by the activation of the MAPK pathways (ERK, JNK, and p38) and AP-1 transcription factors (c-Fos/c-Jun), which upregulate MMP-1 and other matrix metalloproteinases that degrade collagen in the dermal extracellular matrix [38,39,40]. This evidence concerns the gene JUN and skin aging.