STAT3 and breast cancer: To determine whether there are differences between the activities of Chol-siRNA polyplexes and Chol-DsiRNA polyplexes against STAT3 mRNA in syngeneic murine breast cancer epithelial cells, we transfected 4T1 cells with equimolar concentrations of the corresponding Chol-siCTRL, Chol-DsiCTRL, Chol-siSTAT3, or Chol-DsiSTAT3 sequences (Figure 2A) complexed with PLL[30]-PEG[5K] at the indicated N/P ratio and compared normalized murine STAT3 mRNA copy numbers to untreated 4T1 cells 24, 48, and 72 h after treatment by RT-ddPCR (Figure 2B).