VCAM1 and neoplasm: As expected, the tumor concentration of 99mTc-HYNIC-VCAM-1scFv in the blocked mice was significantly lower than that in the unblocked mice (2.92 ± 0.26% ID/g versus 5.51 ± 0.37% ID/g, P < 0.001, Figure 6(b)) at 1 h, while the uptake in nontumor tissues was not significantly reduced by the blocking dose, suggesting that nontumor tissues did not express significant VCAM-1 and took up the tracer nonspecifically.