While treatment with Nutlin-3a, an activator of P5320 that regulates FOXF1 expression30, was comparable in preventing persistent pulmonary hypertension in the EC-Bmpr2-/- mice after reoxygenation, activation of P53 with Nutlin-3a or other small molecules that inhibit MDM2 in cancer patients is associated with adverse systemic effects such as gastrointestinal toxicity, neutropenia and thrombocytopenia61,62. The gene discussed is MDM2; the disease is neutropenia.