FBN1 and systemic sclerosis: Therefore, it is important to demonstrate a role for a candidate molecule in multiple models.[15, 16] For example, the bleomycin model is an inflammation-driven dermal fibrosis model resembling the early inflammatory stages of SSc.[17] In contrast tight skin-1 (Tsk-1) mice develop hypodermal fibrosis due to a tandem duplication of the fibrillin-1 (Fbn-1) gene.