Biodistribution of QE, bivQ and DY-754 8 h p.i. in mice carrying A431/CCK2R and A431/WT xenografts. Semiquantitative fluorescence signals of tumours and organs injected with (a) QE, (b) bivQ and (c) DY-754, or (d) native animals. Bars represent means and standard deviations for n = 5 animals. *p < 0.05, **p < 0.01 (Student's t test of QE or bivQ versus DY-754).