We have examined a number of developmentally regulated transcription factors for expression in Merkel cells and MCC cell lines and demonstrated that their expression patterns may be prognostic in MCC. We have shown that human Merkel cells from adult scalp hair follicle and from neonatal foreskin epidermal sheets express Brn-3c and HATH1. In addition, results demonstrate that the novel Merkel binding activity complex MNF contains Brn-3c. Moreover, Classic lines which retain neuroendocrine phenotype, are slow growing in culture, grow in suspension and are thought to be less aggressive, retain Brn-2, Brn-3c and HATH1 expression, whereas Variant suspension lines which no longer express NE markers retain Brn-2 and Brn-3c expression, but lack HATH1. Further, Type IV Variant lines which grow as adherent monolayers have shorter doubling times, are more radiation- resistant and have higher cloning efficiencies in soft agar, all thought to be indicative of aggressive tumours, have reduced or no Brn-2 proteins and lack expression of Brn-3c and HATH1 transcription factors.