As expected, conditioned medium derived from D2R agonist–treated HUVEC stably transduced with D2R shRNA did not cause a change in apoptosis relative to vehicle-treated shControl HUVEC (Fig. 5b; Supplementary Fig. 7), suggesting that D2R agonist signalling through D2R in endothelial cells is necessary to produce growth factors and cytokines present in the conditioned medium that stimulate apoptosis of the SCLC PDX cells. The gene discussed is DRD2; the disease is small cell lung carcinoma.