To investigate the mechanisms by which PI3Kγ ablation reduces HCC growth in obese mice, we measured the proliferation of liver cells by Ki67 immunostaining of liver sections of the 8-month-old WT mice and PI3Kγ-/- mice kept on a HFD as described in Fig. 1A. Obese PI3Kγ-/- mice showed a reduction in the number of Ki67-positive cells specifically within tumour areas, whereas the number of Ki67-positive cells in non-tumour liver was similar to that of control mice (Fig. 2A,B). Here, MKI67 is linked to neoplasm.