Our lab recently identified radiation responsive microRNAs (miRNA) in colorectal cancer (CRC). The most upregulated candidate, miRNA 451a, inhibited tumor cell proliferation. Gain-of-function experiments confirmed that miRNA 451a regulates calcium-binding protein 39 (CAB39) ribonucleic acid (RNA) and protein levels in CRC. CAB39 is an upstream regulator of the liver kinase B1 (LKB1) and activated protein kinase (AMPK) signaling pathway. Our analysis of The Cancer Genome Atlas (TCGA) data revealed that CAB39 is upregulated at the protein level in a substantial number of CRC patients and correlates with worse overall survival. I hypothesized that CAB39 may have tumor cell intrinsic and extrinsic functions in the CRC tumor microenvironment.