DDR1 and rheumatoid arthritis: The application of the SFA, followed by the application of an unbiased principal component analysis (PCA), demonstrates that 7 remaining DEMs, specifically CD167a and CD1c expressed on mature; IL-7Rα, CD138, and CD324 on immature and SIRPα/β and CD1a on memory B cells (expression shown in heatmap; Figure 2A) have sufficient statistical power to discriminate between ADA+ and ADA− RA patients (Figure 2B); henceforth defined as the “module.”