AR and infection: Since activation of the EGF receptor is important for H. pylori-induced gastrin promoter activation, the absolute levels of mRNA expression were next determined for the EGF family members (HB-EGF, AR, EGF, TGF-α, BTC, epigen, and epiregulin) using qRT-PCR at 1, 2.5, and 5 h post-infection.