RB1 suppression significantly reduced RA-FLS proliferation and significantly activated pro-apoptotic proteins, as demonstrated by the reduced MTT signal (Figure 5B), enhanced caspase-3 activity (Figure 5C), and increased protein expression of cleaved caspase-3 and PARP (Figure 5D) after RB1 down-regulation. This evidence concerns the gene CASP3 and rheumatoid arthritis.