In the Fig. 3e, using Galu pre-treatment RA-FLS cell group as the control, we found that knockdown of HO-1 remarkably reduced cell apoptosis through downregulating Bax and cleaved-caspase-3 expression and upregulating Bcl-2 expression in the Galu pre-treatment cells. Here, BCL2 is linked to rheumatoid arthritis.