Of your input list, 901 genes are known or unknown but not ambiguous. The total number of genes used to calculate the background distribution of GO terms is 7274.

Nodes in the graph are color-coded according to their p-value. Genes in the GO tree are associated with the GO term(s) to which they are directly annotated. To control the graph size, only significant hits with a p-value <= 0.01 and terms descended from them are included.