PON2 and rheumatoid arthritis: When we compared our list of 201 differentially expressed transcripts with the list of genes that have been previously reported to be altered upon vitamin D stimulation by Ramagopalan et. al [16], the only gene that was present on both lists was paraoxonases 2 (PON2), and the expression of PON2 was lower in RA patients than in non-RA patients (FC = -1.37; p = 0.014) (Fig 2).