RPP40 and systemic sclerosis: However, the risk of developing cancer was reduced in the group of 67 patients with anti-Th/To antibodies (anti-hPOP1, -RPP40, -RPP30, and -RPP25 antigens) as compared to the other SSc patients without those antibodies (0% versus 11%; p = 0.009), which suggests their protective role in carcinogenesis.