Freebase(0.00 / 0 votes)Rate this definition: Arbol is a programming language which has been primarily developed for use in Genetic Programming experiments. It is a functional programming language inspired by the ideas of other small and esoteric languages.
Causes. In most cases of colon or rectal cancers, the cause or causes are unknown. Defects in genes that normally protect against cancer play the major role in causing polyp cells to continuously change and become cancerous.
tumor necrosis factor (TNF) either of two lymphokines produced primarily by cells of the immune system, capable of causing in vivo hemorrhagic necrosis of certain tumor cells but not normal cells. They also destroy cells associated with the inflammatory response.