Erbstatin Analog, methyl 2,5-dihydroxycinnamate, is a stable analog of erbstatin, an inhibitor of EGFR (epidermal growth factor receptor)-associated tyrosine kinase. This erbstatin analog is described to be approximately four times more stable than erbstatin in calf serum. Inhibition of EGFR-associated tyrosine kinase by erbstatin analog in EGFR-overexpressing NIH3T3 cells blocked phenotypic changes in the cells mediated through EGFR activity and delayed EGF-induced DNA synthesis, suggesting use of erbstatin analog as a modifier of EGFR-related malignant phenotypic changes of cells. Erbstatin analog is demonstrated to inhibit autophosphorylation of EGFR and the parent compound is described to inhibit autophosphorylation of the oncogene product p60src in A431 cells. Inhibition of thrombin- and thapsigargin- (sc-24017) induced actin polymerization by erbstatin analog is also described, mediated through inhibition of tyrosine kinases and inhibitory towards store-mediated Ca2+ entry. Erbstatin analog has been further employed as a general inhibitor of tyrosine kinases to identify their activity in various biological processes.