Immunoreactivity for p16 was not detected or presented a weak expression in the nuclei of the non-neoplastic epithelia (control group) (Figure 2D) and increased immunoreactivity was observed in the nuclei of penile squamous cell carcinoma samples negative for HPV (p<0.0001, Tukey’s post hoc test) (Figure 2E and I) compared to non-neoplastic epithelia. Here, CDKN2A is linked to squamous cell carcinoma.