PTPA and infection: Dephosphorylation of substrates demonstrated that among the infection-induced phosphatases, pERK serves a better substrate for SHP-1, MKP3 and PP2A (58.6%, 68.3% and 77.9% decrease in phosphorylation for SHP-1, MKP3 and PP2A respectively) (Figure 4G and 4H) whereas MKP1 has a preference for p-p38 (60.2% decrease in phosphorylation for MKP1) (Figure 4G and 4I).