SERPINH1 and systemic sclerosis: Given that we previously observed double-positive cells that are Prosurfactant C+/HSP47+ in the fibrotic, Pump Model lung and in the lungs of SSc patients (Lee et al., 2014) and that we find that Prosurfactant C+ cells are GFP- in reconstituted mice (not shown), we propose that the many of the HSP47+ cells in Region IV will be found to be Prosurfactant C+ cells derived from type II pneumocytes.