CYCS and rheumatoid arthritis: Surprisingly, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) results showed that IL-17 decreased the expression of the ATP- or respiration-related gene NDUFB5, a component of the respiration complex I; UQCRB, CYCS, COX5B and COX7B, components of respiration complex III; and ATP5O, a component of the F-type ATPase found in the mitochondrial matrix, in RA FLSs (Figure 3c).