Uptake of 1 μM Alexa Fluor 488-labeled c[RGDyK]-cryptophane 4 targeting AsPC-1 cells (A–D) and HFL-1 cells (E–H). Micrographs show 4 uptaken by cells after 1 h incubation (A, E). Targeting of 4 was relatively unaffected by co-incubation with 10 μM c[RADfK] (B, F). However, uptake of 4 was blocked by co-treatment with 10 μM c[RGDyK] peptide (C, G) and 0.15 mg mL−1 anti-αv antibody (D, H).