ALK and neoplasm: Consistent with a role for p53 in the suppression of cellular transformation byNPM-ALK, transgenic mice in which NPM-ALK expression is driven from thelymphoid-specific CD2 promoter [30] exhibited accelerated lymphoma development andincreased tumor incidence when the oncogene was expressed on ap53 heterozygous genetic background relative to NPM-ALKexpression on a p53 wild-type background (p<0.0005) (Figure 4C).