MYC and neoplasm: The histopathological features of K14:BRAFV600E-SOX2fl/fl and Ivl:BRAFV600E-SOX2fl/fl tumours were similar to those expressing the wild-type Sox2 allele, including an enlarged epidermis displaying vertical columns of keratinocytes, incomplete maturation of keratinocytes, increased proliferation and MYC and pSTAT3 activation (Supplementary Fig. 9a).