VDR and rheumatoid arthritis: IPA determined two genes within the VDR/RXR activation pathway: Growth arrest and DNA-damage-inducible protein 45 alpha (GADD45A) (FC = 1.47; p = 0.006) and Nuclear Receptor Co-repressor 1 (NCOR1) (FC = 1.21; p = 0.005), that where both up-regulated in RA patients (Figs 1 and 2).