The neighbor-joining tree shows the relation of the mammalian and fish ABCA3-like proteins and their position within the ABCA subfamily. The amino acid sequences of ABCA3 and other related transporters were aligned with the use of Clustal X, and phylogenetic analyses were carried out with the use of Mega2 software (http://www.megasoftware.net/). A maximal parsimony analysis yielded a tree with identical topology. The tree was rooted with human ABCA5 and a related sequence from ciona. A low frequency of nucleotide substitutions per site (as indicated by the length of the horizontal branch) suggests close genetic relatedness. Percentages indicate bootstrap values based on 1000 replicates. Aga denotes Anopheles gambiae, Cin Ciona intestinalis, Dme Drosophila melanogaster, Dre Danio rerio, Hsa Homo sapiens, Mmu Mus musculus, Spu Strongylocentrotus purpuratus, and Tfr Takifugu rubripes. Sequences from drosophila and anopheles are indicated by GenBank locus names. ABC genes from ciona were predicted with the use of a BLAST program (http://genome.jgi-psf.org/ciona4/). The scale bar indicates the number of substitutions per site with the use of the Poisson correction distance method.