A cell-permeable indolyldiketopiperazinyl mycotoxin that inhibits BCRP/ABCG2 (breast cancer resistance protein/ATP-binding cassette G2) multidrug transport activity.
A cell-permeable, reversible, substrate competitive inhibitor of protein tyrosine kinases, including autophosphorylation of epidermal growth factor receptor kinase (IC50 = 2.6 μM).