FOS and melanoma: Thus, the reduced expression of c-FOS in metastatic melanomas would be expected to depend upon the repressive function of miR-221&222 which appear to overcome c-FOS stability.18 It is finally important to point out the extreme effectiveness of HXR9 in the induction of apoptosis in human melanoma cells and the absence of any HXR9-derived toxicity in the normal counterpart, here represented by primary human melanocytes.