Consistent with slightly lower therapeutic activity against primary 4T1 breast tumor growth (Figure 4A), Chol-siSTAT3 polyplexes (Figure 4C, grey bar) suppressed 13% less total Stat3 protein in the primary 4T1 tumors than Chol-DsiSTAT3 polyplexes (Figure 4C, black bar) vs. vehicle alone 48 h after the final IV dose (Day 8) [29 ± 2 (SD) vs. 42 ± 2% suppression]. Here, STAT3 is linked to breast neoplasm.