PLK1 and systemic sclerosis: Additionally, we investigated the composition of infiltrating immune cells in the skin of SSc models and identified 10 key genes, including KIF20A, KIF11, UBE2C, BUB1B, CDK1, CCNB2, AURKB, TOP2A, PLK1, and NCAPG, and were further confirmed to be highly conserved in tree shrews, humans and mice.