We observed significantly more differentially expressed genes between ACVR1 R206H and ACVR1 WT in the presence of H3.1K27M than without and noted that expression of ACVR1 R206H in nestin-expressing brainstem progenitors upregulated genes that have been previously implicated in the mesenchymal subtype of glioma, namely CD44, Snail2, and Tenascin C22,36,37. The gene discussed is SNAI2; the disease is central nervous system cancer.