In mice with B7-H3-expressing xenografts, the tumor uptake of <sup>111</sup>In-labeled proteins (3.6 ± 0.3 and 1.8 ± 0.5%ID/g for [<sup>111</sup>In]In-SYNT179-DOTA and [<sup>111</sup>In]In-AC12-DOTA, respectively) was significantly (<i>p</i> < 0.05, ANOVA) higher than those for <sup>99m</sup>Tc-labeled counterparts (1.6 ± 0.2%ID/g and 0.8 ± 0.2%ID/g for [<sup>99m</sup>Tc]Tc-SYNT179 and [<sup>99m</sup>Tc]Tc-AC12-GGGC, respectively). The gene discussed is CD276; the disease is neoplasm.