While we do not expect all melanocytic cells in the Braf/Pten/Cxcr2WT tumors to be CXCR2 positive due to variation caused by cell cycle and differentiation status, we should not see any CXCR2 positivity in the Braf/Pten/Cxcr2−/− tumor cells. The gene discussed is CXCR2; the disease is neoplasm.