Fig. 7. Ptch1^+/-;Ccnd1^-/- mice develop fewer preneoplastic lesions. (A-E) preneoplastic lesions (indicated by broken lines) express both cyclins D1 (D) and D2 (E) and incorporate BrdU (C). (A,B) Some cells in these lesions, particularly in BrdU-negative regions, are weakly NeuN positive. The density of NeuN positive cells is increased in the molecular layer below the lesion (A,B) when compared with below the mature cluster (F,G). (F-J) Clusters of mature ectopic granule cells (indicated by broken lines) do not incorporate BrdU (H) or express cyclins D1 (I) or D2 (J), and all cells are strongly positive for the post-mitotic neural marker NeuN (F,G). Scale bars: 100 µm. (K) There is a significant decrease in the number of preneoplastic lesions in Ptch1^+/-;Ccnd1^-/- (cycD1 on figure) mice when compared with Ptch1^+/- mice (^*P=0.021), and a smaller total volume of preneoplastic lesions (^**P=0.020), but no significant difference in the number of mature ectopic clusters seen in older adults. ML, molecular layer; IGL, inner granule layer.