HES5 and pulmonary arterial hypertension: Nonconfluent PAH sPASMCs, which are known to constitutively express JAG-1 in an autocrine fashion, were treated with anti-NOTCH3 Ab 28042 and demonstrated a reduction in NOTCH3 ICD and HES-5 proteins, as well as retarded proliferation compared to nonconfluent non-PAH sPASMCs, which do not express JAG-1 [14].