Since tumor cells are known to excrete VEGF in response to a hypoxic environment in vivo, we investigated VEGF excretion as chondrosarcoma spheroids grew in size and developed hypoxia: VEGF excretion, evidence by ELISA on culture media, was detectable from Day 14 spheroids with a value of 10.5 ± 4.2 pg/mL, and increased as the spheroid grew in size (Fig 3B). This evidence concerns the gene VEGFA and neoplasm.