ACVR1B and colorectal cancer: In this study, we have for the first time probed the expression of Nodal and its receptors ALK-4, ALK-7, and Actr-IIB in various types of human colorectal cancer cell lines, CD44-negative or CD24-positive and -negative human colorectal cancer cell lines, human colon cancer tissues, and adjacent noncancerous colon tissue.