Thus, BrafV600E-driven melanoma cells made deficient for COX-1 and -2 (Ptgs−/− cells) fail to form progressive tumors in immunocompetent mice, but their COX-competent parental counterpart (Ptgs+/+) subverts adaptive immunity and grows uncontrollably (Zelenay et al., 2015). The gene discussed is PTGS1; the disease is melanoma.