In an effort to understand the antitumor properties of AZ1366 + irinotecan, we evaluated treatment effects on the WNT signaling pathway on the combination-sensitive CRC explants 010 (APC wt/CTNNB1 wt) and 026 (APC mut/CTNNB1 wt). The gene discussed is CTNNB1; the disease is colorectal carcinoma.