Test of effect of the Pde4b genotype on the number of adenomas in the colon of Apc Min/+ mice over a series of backcross-intercross generations.

Gross tumor numbers were measured in the colons of ApcMin/+ mice from the series of backcross-intercross generations, carrying the Pde4b+/+, Pde4b+/- and Pde4b-/- genotypes. Pde4b+/+ animals (110) show the lowest average colon tumor count 2.4 +/- 2.2. Pde4b+/- animals (192) show higher average colon tumor counts than Pde4b+/+ animals 3.3 ± 2.9. Finally Pde4b-/- mice (66) show the highest average colon tumor number 4.3 ± 4.6. p = 0.0004 by the Kruskal-Wallis Test of association between tumor number and number of mutant alleles of Pde4b. We reject the null hypothesis that there is no difference in gross colonic tumor number as a function of Pde4b genotype.