EGF and central nervous system cancer: The killing effect on U87MGwtEGFR cells was enhanced 8- to 10-fold when PEI25-PEG-EGF was partially replaced with the polyethylenimine (2 kDa)-Melittin conjugate PEI2-Melittin (Figure 1A), and more than 95% of U87MGwtEGFR died within an hour of transfection, again, with no effect on the other glioma cell lines (Figure 1A).