We observed loss of p21Cip1 expression and decrease of p18INK4c expression in PanNET hTS/Men1+/ΔN3-8 tumor tissues (p21Cip1 absent in 5/5 tissues, mean staining score = 5 as described in Methods; p18INK4c reduced or absent in 3/5 tissues, mean staining score = 11.4) compared with age-matched tissues from Men1+/ΔN3-8 mice (p21Cip1 staining score = 180 and p18INK4c staining score = 200) (Figure 5, A and B), suggesting a role for hTS overexpression in downregulating p21Cip1 and to a lesser extent downregulating p18INK4c levels. This evidence concerns the gene CDKN1A and neoplasm.