Although the Gas3/PMP22 protein is expressed at highest levels in differentiated Schwann cells, its presence, albeit at lower levels, in non-neuronal tissues and in NIH-3T3 growth-arrested fibroblasts argues for a more general function of this protein that is uncoupled to myelin structure. We show that gas3/PMP22 overexpression in NIH-3T3 growing cells leads to an apoptotic-like phenotype, which is suppressed by antioxidants and characterized by typical membrane blebbing, rounding up, and chromatin condensation, but with no evidence of DNA fragmentation. REF-52 fibroblasts seem to be completely refractive to gas3/PMP22 overexpression. Recently, several point mutations of the human gas3/PMP22 gene have been associated with Charcot-Marie-Tooth type 1A (CMT1A), a common hereditary demyelinating neuropathy. When gas3/PMP22 point mutations (L16P, $79C, TllSM, and G150D) are similarly overexpressed in NIH-3T3 cells, the induced apoptotic-like phenotype as compared to the wild-type is significantly reduced. Both of the dominant mutations (L16P, $79C~ for CMT1A behave as dominant negatives with respect to the wild type, whereas Tl18M, the only recessive mutant described, behaves as recessive under the same coexpression experiments.These data suggest a role for altered Schwann cell apoptosis in the pathogenesis of CMT1A.