Immunohistochemistry analysis of pancreatic tissue revealed significant differences in the number CD20+ B cells (group 4 vs 2 p=0.01), CD3+ T cells (group 4 vs 1 p=0.01, group 4 vs 2 p=0.03), CD4+ T cells (group 4 vs 2 p=0.003), and CD8+ T cells (group 4 vs 1 p=0.002) in the pancreas of K-Ras mutant mice with developed PC or PanIN (group 4) compared to control mice (groups 1 and 2) (Figures 6A, B). This evidence concerns the gene KRAS and pachyonychia congenita.