FIGURE 3.

Overexpression of Mn-SOD increases global tyrosine phosphorylation of membrane proximal signaling proteins early after TCR engagement. WT, Mn-SOD, and Cu,Zn-SOD overexpressing Jurkat cells were left unstimulated or stimulated by anti-CD3 cross-linking and anti-CD28 for 1, 2, 4 and 6 min. A, cell extracts were analyzed by phosphotyrosine immunoblotting. Immunoblot for GAPDH was used as a control for total protein loading. Protein extracts from Jurkat cells overexpressing Mn-SOD (B) and Cu,Zn-SOD (C) in comparison with WT controls were analyzed by immunoblotting with p-Lck, p-ZAP70, p-LAT, p-PLCγ1, and p-SLP76 Abs. Immunoblots for respective total proteins were used as a loading control.