ACVR1 and diffuse intrinsic pontine glioma: Other mutated ALK2 proteins involved in the genetic disorders FOP and DIPG (Q207E, R258G, G328E, and G356D), unique to FOP (R258S and G325A), and unique to DIPG (G328V) also formed the ICD complexes in a few minutes in response to both BMP7 and activin A (Fig. 3d and Supplementary Fig. 4c).