Treatment with anti‐PD‐L1 alone did not alter tumour volume or weight in HepG2, HepG2.2.15 or HepG2.2.15‐ BMP9 tumour‐bearing mice (Figure 6B, bottom panel; 6C, D blue icon); however, compared with treatment with anti‐PD‐L1 alone, the combination treatment with NK cells and anti‐PD‐L1 significantly reduced the tumour volume and weight (Figure 6B, bottom panel; 6C,D green icon) and resulted in greater number of infiltrating NK cells in HepG2 and especially HepG2.2.15‐BMP9 tumour‐bearing mice (Figure 6E, green icon, Supporting Information Figure S7B). Here, GDF2 is linked to neoplasm.