ACVR1 and neoplasm: In fact, mice that were infected with ACVR1 R206H, H3.1K27M, Cre, and PDGFA had increased tumor incidence (28/31 = 90%) as compared to control mice that were infected with ACVR1 WT, H3.1K27M, Cre, and PDGFA (10/17 = 59%, *p = 0.0220, Fisher’s exact test) or ACVR1 WT, H3.1 WT, Cre, and PDGFA (15/26 = 58%, **p = 0.0059, Fisher’s exact test) (Fig. 4c and Table 2).