Expression of Notch receptors and ligands were detected in the RA synovial tissues (Nakazawa et al., 2001; Ando et al., 2003; Yabe et al., 2005; Ishii et al., 2001) and aberrant activation of Notch1 was observed in primary synoviocyte cultures from RA patients (Nakazawa et al., 2001). This evidence concerns the gene NOTCH1 and rheumatoid arthritis.