VARIANT ACTRIIB PROTEINS AND USES THEREOF

In certain aspects, the present invention provides compositions and methods for modulating (promoting or inhibiting) growth of red blood cells or a tissue, such as bone, cartilage, muscle, fat, and/orneuronal tissue. The present invention also provides methods of screening compounds that modulate activity of an ActRIIB protein and/or an ActRIIB ligand. The compositions and methods provided hereinare useful in treating diseases associated with abnormal activity of an ActRIIB protein and/or an ActRIIB ligand. 在某些方面，本发明提供了用于调节(促进或抑制)红细胞或组织如骨、软骨、肌肉、脂肪和/或神经元组织的生长的组合物和方法。本发明还提供了筛选调节ActRIIB蛋白和/或ActRIIB配体的活性的化合物的方法。本文提供的组合物和方法可用于治疗与ActRIIB蛋白和/或ActRIIB配体的异常活性相关的疾病。