ERBB2 and neoplasm: Moreover, hPEPD treatment of mice bearing ErbB2-overexpressing tumors resulted in strong inhibition of tumor growth, which was accompanied by marked down regulation and decreased phosphorylation of ErbB2 as well as decreased phosphorylation of downstream signaling molecules, such as SRC, AKT, extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription 3 (STAT3) in the tumor tissues [14].