The effects of bee products on in vitro tube formation in HUVECs. A-D) Tube formation was evaluated by measurements of tube area, tube length, joints, and paths after treatment with A) royal jelly (RJ) and GM6001, B) bee pollen, C) Chinese red propolis, and D) caffeic acid phenethyl ester (CAPE), as described in "Methods". GM represents GM6001, a matrix metalloproteinase inhibitor. Data represent means ± SEM (n = 3). ##: P < 0.01 vs. Control, *: P < 0.05, **: P < 0.01 vs. VEGF alone.