BMP4 and systemic sclerosis: The PPI network constructed with the DEGs resulted in 10 hub genes that can be used to differentiate between SSc and RA: LRRK2, IL6, EGF, JUN, CTNNB1, FGF2, BMP2, FOS, BMP4, and EP300. These genes have also been previously highlighted to play a role in the pathogenesis of SSc and RA.