Fig. 6

Blocking surface PD-L1 inhibits tumour sphere formation. Antibody blocking PD-L1 or isotype antibody (Isotype Ab) was added into the sphere culture medium and the blockage of PD-L1 inhibited the sphere number (P < 0.05, a), compared to both untreated and isotype controls. However, the antibody blocking didn’t affect the sphere size (cells/sphere, b)