Activin Receptors, Type I

**Definition:** One of the two types of ACTIVIN RECEPTORS or activin receptor-like kinases (ALK'S). There are several type I activin receptors. The major active ones are ALK-2 (ActR-IA) and ALK-4 (ActR-IB).

**Tree numbers:** - D08.811.913.696.620.682.700.062.500 - D12.776.476.563.062.500 - D12.776.543.750.750.400.820.500.500

**Synonyms:** - Activin Receptor-Like Kinases, Type I