Spi-1l is a new SPI family member. (A) Alignment of Spi-1l and its closest homologous SPI-1/PU.1 proteins. Identical and similar amino acids are indicated in red. Blue boxes identify the different SPI protein domains. (B) Phylogenetic analysis of SPI family members based on the ETS DNA binding domain. GenBank GI (or accession) numbers: human SPI-1 4507175, mouse SPI-1 6755473, cayman SPI-1 8745406, chicken SPI-1 2369863, skate SPI-1 11245497, zebrafish SPI-1 AF321099, cichlid SPI-1 8745412, zebrafish Spi-1l EU685253, human SPI-B 36562, monkey SPI-B AF025395, mouse SPI-B 2586116, cayman SPI-B 8745407, Xenopus SPI-B 8745409, skate SPI-D 11245499, lamprey SPI 8745404, human SPI-C BC032317, Xenopus SPI-C BC077851, cichlid SPI-C 8745414, skate SPI-C 11245501, mouse SPI-C 6755618, and human EFL5 4557551. The phylogenetic tree is built using the neighbor joining method. Length of horizontal branches is proportional to the evolutionary distance between the protein molecules. The value at each node represents the probability that that branch length is not zero. This tree indicates that Spi-1l is most related to SPI-1 of all the SPI family members.