NFKB1 and colorectal cancer: For example, the active metabolite (SN38) of the colon cancer therapeutic irinotecan (CPT-11) was shown to activate NF-κB in most colorectal cell lines in vitro. Blocking activation of NF-κB enhanced both the cytotoxicity of SN38 in vitro and the sensitivity of tumours to CPT-11 in a murine colorectal cancer xenograft model (Cusack et al, 2000).