To investigate the mechanism responsible for the lack of IL‐1α protein synthesis in LPS‐activated HA‐FLS and RA‐FLS, as compared to non‐HA‐FLS and HR‐FLS, cells were incubated with LPS for 6 hours, and then for another 2 hours, with 5 μg/mL actinomycin D. After 2 hours of actinomycin D treatment, IL‐1α mRNA decreased drastically in both LPS‐activated HA‐FLS (Figure 3A) and LPS‐activated RA‐FLS (Figure 3C), yet neither in LPS‐activated non‐HA‐FLS (Figure 3B) nor HR‐FLS (Figure 3D). Here, IL1A is linked to rheumatoid arthritis.