HPK1 activity enhances spontaneous and TCR-mediated apoptosis in primary CD4⁺ T cells.

(A) CD4⁺ T cells from LNs of DO 11.10 TCR tg mice were stimulated with OVA peptide for 24 hours and infected with the indicated retroviruses. After 3 days of expansion, the cells were either left untreated or restimulated with plate-bound αCD3ε mAb for 8 hours and analyzed by FACS. Mean values from 5 independent experiments are shown. (B) Expression of HPK1 proteins after transfection of retroviral vectors expressing pHA-HPK1 wt (lane1), pHA-HPK1 wt N-terminus (lane 2), pHA-HPK1 wt C-terminus (lane 3), pHA-HPK1 M(46) (lane 4), or pHA-HPK1 M(46) N-terminus (lane 5) into 293T cells. Forty-eight hours after transfection, 40 μg cellular proteins was electroblotted and assayed using an αHA mAb.