KRT5 and squamous cell intraepithelial neoplasia: Furthermore, the expression of SOX2 also supports our earlier findings19 that solitary AIS can express markers of squamoid differentiation such as keratin 5 and p63 or could be the result of the gain of chromosome 3q harbouring the SOX2 gene.44, 45 AIS has been reported to be associated with SIL in 25–75% of cases.13, 16, 19, 46 The concurrence of both types of lesion in the same biopsy supports the hypothesis that both lesions may arise from a single progenitor cell or area at risk.