KITLG and systemic sclerosis: However, conditioned media from cultured fibroblasts was characterised by elevated soluble SCF levels in SSc patients compared to the controls Since earlier studies have also shown that SCF expression was markedly higher in active skin lesions in SSc (oedematous phase) compared to inactive (atrophic phase) lesions, it is likely that this pathway contributes to the overall disease process, through paracrine signalling as well as mast cell recruitment into the lesions.