FOS and systemic sclerosis: It has been reported that microvascular endothelial cells exposed to SSc-derived Abs mediate PAR-1 activation that engages a signaling cascade including ERK1/2-dependent activation of PI3K/AKT/mTOR/p70S6K and AP-1/c-FOS to activate the IL-6 promoter, leading to elevated secretion of IL-6 in a time- and dose-dependent manner (6).