ELP1 and neoplasm: To examine the significance of FD in epidermal carcinogenesis, FD expression was investigated in an immortalized nontumorigenic cell line (HaCaT) derived from human epidermal keratinocytes as well as three Ha-ras-transformed HaCaT cell lines (A5, II-4 and RT3), which are representative in vitro models for the progressive stages of cSCC tumor.