Expression of the mRNA encoding flagellar proteins during the Trypanosoma brucei cell cycle. (1) Early G1: cells with one flagellum. (2) Late G1: maturation and duplication of the basal body. (3) S phase: construction of the new flagellum. (4) G2/M phase: elongation of the new flagellum. IFT, basal body, and membrane and matrix genes peak first, whereas axoneme and PFR transcripts emerge later when flagellum elongation takes place. Original data are from Archer et al. and transcripts encoding proteins belonging to different structures are listed in Additional file 1: Table S1. IFT, intraflagellar transport; PFR, paraflagellar rod.