Differential murine T-cell proliferation response to treatment with trametinib in vitro. CFSE-stained splenocytes from wild-type and AML mice were treated in vitro with anti-CD3, trametinib, and/or anti–PD-1 and incubated for 3 days. (A,C) Mean ± standard deviation (SD) percentage of dividing T cells for wild-type and AML mice from 3 independent experiments. (B,D) Representative flow cytometry plots of T-cell division according to treatment condition gated on live CD3⁺ cells from 1 of 3 independent experiments for both wild-type and AML mice. (E) Proliferation index for T cells from wild-type and AML mice stimulated with anti-CD3 and treated with trametinib 0, 10, or 100 nM. (A,C) Displaying Tukey pairwise comparisons for unstimulated vs all other treatment conditions; statistically significant results displayed as: ***P < .001.