Effects of flavonoids on the kinase activity of liver tumour proteins. Liver tumour extracts of 50 μg proteins were incubated with various flavonoids (20 μM) in the presence of [γ-32P]-ATP. Lanes: 1, control; 2, luteolin; 3, quercetin; 4, d-catechin; 5, genistein; 6, taxifolin.