In Vitro: HPK1-IN-35 (compound 31) (0.1, 0.3, 1, 3 µM; 1 h) decreases the expression of p-SLP76 stimulated by anti-CD3 antibody (1 µg/mL) in a dose-dependent manner. HPK1-IN-35 (0-10 µM; 24 h) promotes IL-2 secretion in Jurkat cells in a dose-dependent manner with EC50 values of 1.19 μM.