TGFB1 and cancer: To evaluate the in vivo effect of TGF-β1 inhibition by APT-β1-OMe-P, a xenograft cancer model was used to assess the anti-tumor effect of APT-β1-OMe-P alone or in combination with the tyrosine kinase inhibitor, gefitinib, before and after the drug withdrawal interval (study design shown in Figure 4A).