Tyrphostin AG 1478 is a tyrosine kinase inhibitor that has been demonstrated to be a selecetive and potent inhibitor of EGFR (Epidermal Growth Factor Receptor ) in a variety of cell lines with an IC50 of about 3 nM. In Rat-1 fibroblasts, Tyrphostin AG 1478 was demonstrated to downregulate EGF-stimulated DNA synthesis. The induction of p21/ip1/WAF1 and activation of EGF-dependent src-family kinase was noted to be blocked by Tyrphostin AG 1478 in the epidermoid carcinoma cell line A431. Additionally, a study utilizing early-weaned rats to study EGFR signaling and its role in mucosal cell proliferation, the administration of Tyrphostin AG 1478 was noted to decrease ERK phosphorylation without affecting p-Src and p-Akt. Tyrphostin AG 1478 was also noted to reduce measures of mitosis and DNA synthesis in this study. As EGFR is found to be overexpressed in various cancer cells, there may be research interest in compounds that inhibit EGFR, such as Tyrphostin AG 1478.