Phylogenetic analysis of the DNA-binding domains shows that BFD1 and syntenic orthologs from other tissue-cyst-forming species comprise a clade with human c-Myb, distinct from CDC5L-like sequences, with their first and second domains displaying homology to the R2 and R3 repeats of the prototypical c-Myb, respectively (Figures 2A and 2B; Figure S2B). This evidence concerns the gene CDC5L and cyst.