CDK1 and pulmonary arterial hypertension: In the case of HPASMC obtained from PAH patients, we are finding that their protein levels of CDC2 are much higher than in cells from control donors Figure 1A. This is seen in cell cultures grown in low proliferative (quiescence) medium 0.2% fetal bovine serum (FBS) and high -proliferative growth medium (5% FBS).