Statistical analysis of pigmented skin abnormalities (PSA). A: Overview of the inner side of skins from HDGFTyr/Ink4a+/-, Ink4a+/-, and HDGF-/-/Ink4a+/- mice showing PSA. Scale bar equates 1 cm. B: Statistical analysis of the occurrence of (PSA) of the different genotypes. HDGFTyr/Ink4a+/- n = 23, Ink4a+/- n = 24; HDGF-/-/Ink4a+/- n = 23. C: Chi-square contingency table was applied for the category: largest PSA was ≤ 1mm or > 1mm. Contingency tables were carried out for the following pairs of genotypes: HDGFTyr/Ink4a+/- - HDGF-/-/Ink4a+/- and Ink4a+/- - HDGF-/-/Ink4a+/-. Analysis was regarded significant for p < 0.01.