(From the Medford News). "In humans, scientists and medical doctors documented the aging skin phenotype a long time ago, and the [gene] Smad7 over-expression in aged skin was reported a few years ago, but nobody knew whether these two events had any link ... They found that Smad7 over-expression shifts the epidermal stem cell differentiation program from forming hair follicles to sebaceous glands, causing the mice to exhibit balding and oily skin. ... independent of its normal role in blocking signaling from a group of genes called Smad, Smad7 shuts down signaling of another group of genes called Wnt ... Wnt signaling is critical for organ development, but if Wnt signaling is too active, it also causes cancer." Once again, aging or cancer is the choice in an aspect of our present biochemistry; many of the changes seen in aging turn out to have something to do with cancer suppression.