CHUK and sarcomatoid carcinoma: Altogether, these changes make C57-N-IKKα cells appear as potentially more aggressive, since Snail1 is considered a determinant of the progression of carcinomas [27], c-Myc expression is found in skin SCCs of poor prognosis [57], and the downregulation of the expression of keratins, including that of K5 in skin tumors, is associated with increased malignancy and conversion to spindle cell carcinomas [58].