PF299804 (Dacomitinib) is a potent, irreversible pan-HER inhibitor with IC₅₀’s of 6, 46, and 74 nM for ErbB1(HER1), ErbB2 (HER2), and ErbB4 (HER4), respectively. PF299804 inhibits ErbB1 autophosphorylation in A431 cells with an IC₅₀ of 15 nM.