SMAD1 and rheumatoid arthritis: As a point of interest, the canonical pathway in IPA which shares the highest overlap with the regulators in this causal network is the pathway called ‘Role of Osteoblasts, Osteoclasts and Chondrocytes in Rheumatoid Arthritis’, (containing SOST, the Smad family, SMAD1, BMP6, and RUNX2), indicating the relevance of SOST and its downstream targets both in bone homeostasis and inflammatory disease.