The overexpression of fatty-acid synthase (FAS) is obesity-related [29], our data show the expected up-regulation of this protein in HDF mice tissue but, a down regulation in WA and WA-TNF-α spheroids, this finding is related to the fact that the spheroids were not exposed to circulating fat as occurs in animal tissue. This evidence concerns the gene FASN and obesity due to melanocortin 4 receptor deficiency.