GDF2 and pulmonary mucoepidermoid carcinoma: First, we analyzed the expression of BMP receptors and the downstream target gene TMEM100 in human primary pulmonary arterial endothelial cells (PAEC), human microvascular endothelial cell line (HMEC), human primary bronchial epithelial cells (PBEC), and the human epithelial pulmonary mucoepidermoid carcinoma cell line NCI-H292 (Figure 11A) and tested their sensitivity to BMP9, by examining the expression of ID1, which is a direct target gene of BMP/SMAD signaling (Figure 11B).