ATM and systemic sclerosis: Further evidence of the pathogenicity of both ATA and ACA also derives from the fact that in-vitro stimulation of human dermal fibroblasts with such antibodies can induce a significant increase in profibrotic markers and apoptosis resistance [81], and that incubation of calf pulmonary arterial endothelial cells with SSc sera containing ACA and ATA is able to accelerate endothelial cell aging [82].