SB-505124是一种选择性 TGF-β 受体 I 型受体 (ALK4、ALK5、ALK7) 抑制剂，对 ALK4 和 ALK5 的 IC50 值分别为 129 nM 和 47 nM，不抑制 ALK1、2、3 或 6。

EW-7197 is a selective inhibitor of TGF-β receptor ALK4 and ALK5 with IC50s of 13 nM and 11 nM.

LDN-212854 is an inhibitor of BMP and can inhibit ALK2 with IC50 of 1.3 nM. It is used to prevent heterotopic ossification.