Heterodimers of placenta growth factor vascular endothelial growth factor – endothelial activity, tumor cell expression, and high affinity binding to Flk-l/KDR - Cao, Y H; Chen, H; Zhou, L; Chiang, M K; Anandapte, B; Weatherbee J, A; Wang, Y D; Fang, F Y; Flanagan, J G; Tsang, M LS (J. Biol. Chem, 1996)