COL3A1 and rheumatoid arthritis: Moreover, as the results of pseudotime analysis and RA pathophysiology suggest a potential transition from IL-1b-producing M1 Mp to anti-inflammatory COL3A1+ Mp (Figure 3B), we attempted to induce COL3A1+ Mp by stimulating THP-1-derived M1 Mp with TGF-β1 for 96 h (Figure 6A).