PEA and URB597 increase tumor necrosis. Tumors treated daily by co-administration of PEA and URB597 were excised after six days of treatment and tumors treated by vehicle were excised after five or six days. (A) Quantification of necrotic regions was realized using Haematoxylin and Eosin staining (n = 5). Significantly different (*P < 0.05; **P < 0.01) from vehicle administration. (B) Pictures show representative histological H-E stainings performed on tumor slices. (C) Apoptosis was evaluated by TUNEL assay (n = 6-12). (D) PEA and URB597 do not affect angiogenesis. HUVEC were seeded (104 cells/well in microwells) and incubated with PEA (10 μM) and/or URB597 (10 μM). The angiogenic potency was determined by measuring the number of tube intersections formed after 24 h plating on Matrigel (n = 2). (E) Tumor vascularization was evaluated by CD31 immunostaining of tumor cryosections and blood vessel area was expressed as percentage of the total area (n = 5).