BMP9 expression causes up-regulation of secreted regulatory factors. (A) RT-PCR of control and BMP9-transduced SV40-transformed SVECs. (B) Real-time quantitative RT-PCR measurement of endoglin and ALK1 expression in HUVECs (with and without BMP9 treatment for 24 hours) and SVECs (control and constitutively expressing BMP9). (C-D) Quantitative ICAT-based mass spectrometry (top panels) and collision-induced decay MSMS-based (MSMS-CID) protein sequence identification (bottom panels) of the chemokines CXCL12 (SDF1, C) and CXCL10 (IP10, D) in SVECs transduced with BMP9. (E) Transwell migration of BMP9-expressing and control SVECs, in the presence and absence of a neutralizing anti-SDF1 antibody. P values are from experiments conducted in triplicate.