RAC1 and in situ carcinoma: Tumors associated with high UV exposure, such as melanoma in situ, lentigo maligna, and desmoplastic melanoma, are most commonly related to mutations in BRAF (other than p.V600E), neurofibromatosis type 1 (NF1), and Ras-related C3 botulinum toxin substrate 1 (RAC1) [1,4,5,7].