CD274 and carcinoma: Because TGFβ accumulation may occur at the invasive front in carcinomas (27, 28), we simulated tumors with either a homogeneous TGFβ field or a TGFβ gradient (Figure 4A and Videos S2, S3), in the absence or presence of IFNγ inhibition (either by PD-L1 or by TGFβ).