ALDH1A1 and colorectal adenoma: Bartley and colleagues (15) used aldehyde dehydrogenase isoform 1A1 (ALDH1A1) as a marker to identify SCs in precancerous colorectal adenomas and found that adenomas located in the right site of the colon tended to express a higher level of ALDH1A1 labeling indices than those in the left site of the colon.