To determine which immune or stromal cells might be activated by the proNGF/p75NTR axis in synovial tissue, we investigated the expression of p75NTR, TrkA and SORT1 in previously published scRNAseq data sets referring to whole synovial tissues (total 118.622 cells) derived from treatment-naïve RA patients or from RA in sustained clinical and imaging remission (Figure 1A) (27). This evidence concerns the gene SORT1 and rheumatoid arthritis.