CXCR2 and neoplasm: Flow cytometry was first performed on the skin of adult Braf/Pten/Cxcr2WT and Braf/Pten/Cxcr2−/− mice immediately after application of 4-HT (prior to tumor formation), and we confirmed that melanocytes do become GFP-positive in both genotypes and that Braf/Pten/Cxcr2−/− mice lose expression of CXCR2 as expected (Figure S2D).