Secreted frizzled-related protein 2 (sFRP2), functioning as a melanogenic stimulator through β-catenin signaling in human melanocytes, is overexpressed in melasma, solar lentigo, and acutely UV-irradiated skin, and fibroblast-derived sFRP2 may be closely related to the regulation of skin pigmentation [114]. This evidence concerns the gene SFRP2 and freckles.