PTEN and neoplasm: To more directly assess the requirement of PI3K activity, we co-expressed of a dominant negative allele of the Phosphoinositide 3-Kinase PI3K gene, Dp110/PI3K92E(Dp110DN) in Src64B + RasACT eye disc clones also reduced tumour size (Figure S7G,H and Table 4), although not as potently as with PTEN (Figure 8E,F).