CREB1 and idiopathic pulmonary arterial hypertension: In PAH, a rise in [Ca2+]cyt in PASMC due to enhanced SOCE/ROCE (due to upregulated SOC/SOC components) and voltage-dependent Ca2+ entry in PASMC from IPAH patients also activates many signal transduction proteins (e.g., CaMK, PKC, and MAPK) and transcription factors (e.g., AP-1, NFAT, CREB, and NF-κB) thus influencing gene expression and promoting cell proliferation.