PLK1 and neoplasm: In addition, LP-HAPC-2mol%FA-PEG2000, LP-OH-1mol%FA-PEG2000, and LP-OH-C-2mol%FA-PEG2000 lipoplexes with PLK1 siRNA selectively suppressed the growth of tumor cells via down-regulation of PLK1 mRNA (Figure 8 and Figure 9), indicating that their FA-PEG-modified siRNA lipoplexes were selectively taken up by the FR-expressing cells, and then suppressed the expression of target genes in the cells.