Fig. 1.

Endogenous expression of activation-induced cytidine deaminase (AID) in rheumatoid arthritis-fibroblast-like synoviocytes (RA-FLS) lines. (a) The ectopic transcription of AID was detected in RA-FLS lines by reverse transcription–polymerase chain reaction (RT–PCR). The expression of two other APOBEC family members (APO1: APOBEC1, APO3G: APOBEC3G) was also examined by RT–PCR. (b) AID mRNA was quantified (relative quantification) by real-time PCR and normalized to housekeeping gene, GAPDH and fold expression over that of OA-FLS (OA2) was calculated by ΔΔCT method in triplicate. The grey bars and error bars indicate the averages and standard deviations, respectively, of two independent experiments. (c) Crude protein extracts from the representative FLS lines were analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE)/immunoblotting using anti-human AID polyclonal antibody (upper panel) or anti-β-actin (lower panel).