All animal experiments were approved by the University of South Florida Institutional Animal Care and Use Committee. Mice were housed in pathogen-free facilities. Tg.AC mice described previously (Tepper et al., 1990 (link)) were obtained from Taconic. S100A9Tg mice on FVB/N background (Cheng et al., 2008 (link)) and S100A9KO mice on C57BL/6 background (Manitz et al., 2003 (link)) were described previously. BALB/c, C57BL/6, and FVB/N mice were obtained from the National Cancer Institute, and OT-1 mice were obtained from the Jackson Laboratory. In S100A9Tg;Tg.AC bitransgenic mice, the presence of S100A9-IRES-GFP transgene was verified by the expression of GFP in leukocytes from peripheral blood, and the v-h-ras transgene was detected by genomic PCR for the SV40 sequences. In some experiments, S100A9Tg mice on C57BL/6 background were used after backcrossing S100A9Tg FVB/N mice with C57BL/6 mice for nine generations.