FBXO3 and infection: In agreement with this report, and further supporting the notion that FBA negatively regulates the expression of katG in infected cells, our qRT-PCR analysis (Fig. 5d) showed that katG expression was 7-fold up-regulated in the ∆fba mutant compared to WT, at 24 h of infection, in J774-1 macrophages supplemented with glucose and glycerol.