Bicistronic CAR T cells have reduced phosphorylation of CD3ζ and downstream signaling molecules compared with monospecific CAR T cells, after stimulation. (A) Western blots showing levels of phosphorylated and total protein for the indicated analytes from monospecific CD79a, CD19, and bicistronic CD19-79a CAR T cells at baseline (0 minute) and 30 minutes after stimulation by immobilized CD19 or CD79ab recombinant protein. (B) Log2 values of normalized band intensities measured by densitometry from 3 independent experiments. ∗∗P < .01 and ∗P < .05 were calculated with paired two-tailed t test.