• BMP9 is a secreted protein and after binding to its receptors, SMAD family transcription factors were recruited and activated, leading to gene expression.
• Homozygous mice expressed the human BMP9 and developed normally.
• This model is useful in studying the role of BMP9 in liver fibrosis.

Strain specific analysis of BMP9 mRNA expression in wild-type C57BL/6N mice and homozygous B-hBMP9 mice by RT-PCR. Liver RNA were isolated from wild-type C57BL/6N mice (+/+) and homozygous B-hBMP9 mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human BMP9 primers. Mouse Bmp9 mRNA was detectable only in wild-type C57BL/6N mice. Human BMP9 mRNA was detectable only in homozygous B-hBMP9 mice but not in wild-type mice.