Given that the overexpression ratio of ASCT2 between BxPC3 and HEK293 cells (Supplementary Fig. S14) is comparable to that in clinical studies7, 18, 19, the tumour-selective interaction of the polymer as shown in Fig. 3 strongly indicates the potential in vivo activity of our synthesized polymer for tumour-targeting ligand. This evidence concerns the gene SLC1A5 and neoplasm.