Interestingly, in nude mice implanted with U87MG-LacZ/AS cells, the presence of solitary β-gal+ tumor cells in the brains was limited to the injection tracts (not shown) and could only be seen in mice sacrificed by day 35, when tumor volumes were measured, suggesting that reduced IGF-IR levels eventually caused the death of all U87MG cells. This evidence concerns the gene IGF1R and neoplasm.