Lack of Gas6 mRNA and protein in Gas6^–/– mice. (a) Southern blotting of genomic DNA from the progeny of intercrosses of Gas6 heterozygous mutant mice. The genomic DNA from wild-type mice (+/+), heterozygous mice (+/–), and Gas6^–/– mice (–/–) was digested with EcoRV and hybridized with the probe described in Figure 1. The upper and lower bands correspond to the wild-type and targeted alleles, respectively. (b) Northern blotting of Gas6 mRNA in wild-type (WT) and Gas6^–/– (KO) mice. mRNA prepared from kidney of wild-type and Gas6^–/– mice was subjected to Northern blotting. GAPDH was used as internal control. (c) Western blotting of Gas6 in wild-type and Gas6^–/– mice, using lysates prepared from spleen.