(A) The protein domain structure of the SpFGFA contains a signal peptide and a FGF core domain. (B) Phylogenetic analysis of FGF proteins. The tree was constructed by the neighbor-joining method based on the multiple alignments of the FGF core domains from various organisms. Bootstrap values over 50% are shown at the branch points. Sea urchin FGFs (Sp-FgfA and Pl-FgfA) do not group with the seven vertebrate FGF families from A to G. The scale indicates the % amino acid difference with Poisson correction. GenBank accession numbers for FGFs are: acorn worm SkFgf20 like, NM_001171225; amphioxus AmphiFgf1/2, EU606032; AmphiFgf8/17/18, EU606035; AmphiFgf9/16/20, EU606036; ascidian CiFgf8/17/18, NM_001032476; CiFgf11/12/13/14, NM_001032561; Caenorhabditis elegans CeEGL17, NM_075706; Drosophila melanogaster DmPYR, AY55396; DmTHS, NM_136857; human HsFgf19, NM_005117; mouse MmFgf1, NM_010197; MmFgf2, NM_008006; MmFgf3, Y00848; MmFgf4, NM_010202; MmFgf5, NM_010203; MmFgf6, NM_010204; MmFgf7, NM_008008; MmFgf8, NM_010205; MmFgf9, U33535; MmFgf10, NM_008002; MmFgf11, NM_010198; MmFgf12, NM_183064; MmFgf13, NM_010200; MmFgf14, NM_010201; MmFgf15, NM_008003; MmFgf16, AB049219; MmFgf17, NM_008004; MmFgf18, NM_008005; MmFgf20, AB049218; MmFgf21, NM_020013; MmFgf22, NM_023304; MmFgf23, NM_022657; sea urchin Sp-FgfA, HQ107979; Pl-FgfA, EF157978.