CD19 and cancer: To demonstrate controllable synthetic cell-to-cell communication, we diversified the CD19 levels on target SCASA yeast cells by GPCR stimulation, to simulate cancer cells with varying CD19 antigen densities, and performed co-cultivations with CAR Jurkat NFAT-Luc cells at a low target-to-effector cell ratio of 0.2x (Fig. 3a).