CUBN and neoplasm: However, given the comparably low overall renal PSMA expression compared with tumor (Fig. 5), the observed greater than 20-fold-higher (and only partly blockable [Fig. 3]) uptake of 68Ga-PSMA-I&F in the kidney than in the LNCaP xenograft is strongly indicative of alternative, non–PSMA-mediated uptake mechanisms, such as megalin/cubilin-mediated tubular reabsorption (48), being involved in the renal handling of PSMA-targeted tracers.