Inhibition of P-glycoprotein at the blood-brain barrier by phytochemicals derived from traditional Chinese medicine - Mahringer, A; Karamustafa, S; Klotz, D; Kahl, S; Konkimalla, V B; Wang, Y; Wang, J; Liu, H Y; Boechzelt, H; Hao, X; Bauer, R; Fricker, G; Efferth, T (Cancer Genom Proteom, 2010)