Previously, we have shown that FLS from the persistent oligoarthritis disease course overexpress BMP4 and have a chondrocyte-like phenotype [15, 16, 25] when compared to normal FLS; therefore, we investigated the chondrocyte-like phenotype in three different JIA subtypes: persistent, ETB, and polyarticular. This evidence concerns the gene BMP4 and juvenile idiopathic arthritis.