Effects of 4-MU and tumour cell targeted shHAS3 on proliferation in OSC1 xenografts. (A) 4-MU, staining of human Ki67 (red) was markedly reduced by 4-MU treatment and confined to the interface between tumour cells and stroma. (B) shHAS3, staining of human Ki67 (red) was markedly reduced in tumour cells transduced with shHAS3. Scale bars 200 μm. Shown are representative images of n = 6 (control) and n = 7 (shHAS3) experiments.