HPK1 affects NF-κB induction in murine T cells.

(A) HPK1 wt supports and the HPK1 C-terminal peptide suppresses NF-κB induction. EL-4 cells were cotransfected with expression vectors encoding HPK1 wt or HPK C-terminus and a luciferase reporter gene driven by 3 copies of a κB site from the c-myb enhancer.9 Forty-two hours after transfection, cells were either left uninduced (–) or induced with 500 μM H₂O₂ for 6 hours as indicated. The data show mean values of 4 transfections. (B) HPK1 C-terminus impairs IκBα degradation. CD4⁺ T cells from LNs of DO 11.10 TCR tg mice were stimulated with OVA peptide and infected with the indicated retroviruses. After 2 days of expansion, the cells were sorted for infected EGFP-positive cells. One day later the cells were either left untreated (–) or restimulated with plate-bound αCD3ε mAb for 30 minutes (+). Whole cell protein extracts were prepared from 3 × 10⁵ cells each and immunoassayed using the indicated Abs.