The number of total (CD31+) and functional (DiOC7+) blood vessels per tumor area (left panels), and the percentage of functional blood vessels (right panels) present on Day 0, 2, 4, 8, and 12 in A431 xenografts following a single dose of A) paclitaxel (25 mg/kg, i.p.), B) doxorubicin (8 mg/kg, i.v.), or C) 5-FU (100 mg/kg, i.p.). Bars represent the mean of 5-6 tumors; error bars represent standard error of the mean (SEM). Symbols represent statistical significance for total (*), functional (♦), and percent functional (+) blood vessels as compared to control (Day 0) tumors.