While this p5RHH oligonucleotide condensing, endosomolytic NP system has previously been used in vivo to successfully silence canonical NF-kB signaling in macrophages in models of rheumatoid arthritis and osteoarthritis [27, 28], we first wanted to assess the ability of this system to deliver siRNA into the cytoplasm of cancer cells in vitro. Here, NFKB1 is linked to rheumatoid arthritis.