In studies using synoviocytes and articular chondrocytes from RA patients, 1,25-(OH)2D3 was shown to regulate matric metalloproteinases and prostaglandins, but only in the presence of IL-1β [158], suggesting, as outlined earlier, that 1,25-(OH)2D3 is only effective as a regulator of synoviocytes in the setting of RA disease inflammation. This evidence concerns the gene IL1B and rheumatoid arthritis.