PTGS2 and carcinoma: Among mice of the same genetic background, tongue tumor incidence/multiplicity and carcinoma incidence were significantly higher in homozygous ZD:Cox-2−/−vs. ZS:Cox-2−/− or heterozygous ZD:Cox-2+/−vs. ZS:Cox-2+/− mice, but not in ZD:WT vs. ZS:WT mice (Fig. 1a and b, Supporting Information Table 1), demonstrating that combined ZD and Cox-2 ablation led to a worse tumor outcome.