AG 556 (Tyrphostin AG 556) is a highly selective EGFR kinase inhibitor. AG 556 reversibly inhibits the human ether á-go-go gene potassium channels (hEAG1 or Kv10.1) with IC₅₀s of 6.1, 6.7 and 5.8 μM for inhibiting WT, Y376A and Y479A hEAG1 channels^[1]. In Vitro: AG 556 is an EGFR substrate-site competitor. AG 556 (1-10 µM) inhibits GB1B cells and AC1B cells growth in a time and dose dependent manner^[2].
AG 556 (10 and 50 μM) is effective in inhibiting the phosphorylation of p42^MAPK/ERK2 and p44^MAPK/ERK1[3]. In Vivo: Inhibition of EGFR kinase by AG 556 (5 mg/kg; i.p.) exerts an antiarrhythmic effect in the rat model of reperfusion-induced arrhythmias^[4].