GPR55 and malignant colon neoplasm: To determine if cannabinoid receptor messenger RNA (mRNA) expression levels vary in our cell line panel (seven colon cancer cell lines, a normal colon epithelial cell line, and HEK 293 cells), we conducted reverse transcribed-quantitative polymerase chain reaction (RT-qPCR) analysis of the four most common cannabinoid receptors (CNR1, CNR2, GPR55, and TRPV1).