A 4:1 mixture of phenylacetate and phenylacetylgluatmine, degradation products of the antineoplaston agent A10. Antineoplaston AS2-1 inhibits the incorporation of L-glutamine into tumor-cell proteins, leading to cell cycle arrest in the G1 phase and inhibition of mitosis. This agent may also inhibit RAS oncogene expression and activate tumor suppressor gene p53, resulting in cell differentiation and apoptosis.