We also showed that sarcoma-like cells (SCLs) derived from a single CTEPH patient could be isolated at the second passage of the myofibroblast-like cells, and these had an increased expression of matrix metalloproteinase-14 (MMP-14), and had high tumorigenic potential to form solid and undifferentiated tumors which grew along the intimal surface of the pulmonary arteries in C.B-17/lcr-scid/scidJcl mice [5]. Here, MMP14 is linked to sarcoma.