Fig. 2

A Inducible expression of LdCK—Non-transduced (NT), conventional HER2 CAR, cRB-340-1 and RB-340-1 cells were stimulated at a 1:1 effector to target ratio with beads coated with bovine serum albumin (BSA), low or high densities of HER2 ectodomain (Low HER2 and High HER2) or the HER2⁺ FaDu cells and tested for expression of the HER2-TEV-linked tag tNGFR or the LdCK-linked tag Q8 at day 3 and 5 following stimulation; percentages of each cell population are displayed in the respective quadrant. B Modulation of cellular function by RB-340-1—PD-1 surface expression, IL-2 secretion and T cell proliferation after exposure of CAR-T cells to the FaDu cell line for 6 days at 1:5 and 1:20 E:T ratios. C Kinetics of RB-340-1 cellular function—representative kinetics of PD-1 expression, IL-2, IFN-γ and TNF-α secretion, cytotoxic activity and CAR-T cell expansion after stimulation with FaDu cells at 1:5 effector-to-target ratio. Similar results were obtained at 1:20 effector to target ratio (not shown). Only RB-340-1-related p values are ranked by the asterisks in all panels, in the lower panel the blue hyphens around the asterisks refer to statistical differences between RB-340-1 and conventional HER2 CAR and the gray between RB-340-1 and cRB-340-1. The complete statistical matrixes are shown by Additional file 6: Table S1 here and thereafter