CHRDL2 is a novel chordin like protein that can act as a BMP antagonist. A member of the chordin family of proteins, it contains a signal peptide and three CR (cysteine-rich repeat) domains. When expressed as a recombinant protein it is secreted and binds to activin A, but not to BMP-2, -4, -6. Differential expression has been detected in developing chondrocytes, myoblasts, osteoblasts, and osteoarthritic joints. Complex alternative splicing of CHRDL2 potentially results in distinct isoforms that differ at their C termini, in the expression of signal peptide, and in the content of CR domains. CHRDL2 was originally characterized as a novel protein exclusively expressed in breast, lung, and colon tumors.