ARG1 and rheumatoid arthritis: In another study, the differential gene expression analysis revealed nine significantly upregulated genes in RA-ILD compared to RA without ILD: arginase 1 (ARG1), thymidylate synthetase (TYMS), sortilin 1 (SORT1), a marker of proliferation Ki-67 (MKI67), olfactomedin 4 (OLFM4), a baculoviral inhibitor of apoptosis repeat containing 5 (BIRC5), membrane-spanning 4-domains A4A (MS4A4A), C-type lectin domain family 12 member A (CLEC12A), and the long intergenic non-protein coding RNA (LINC02967).