TPCN1 and pulmonary arterial hypertension: NAADP induced PASMC proliferation, whereas TPC1 knockdown alone did not cause an apparent change in the proliferation of PASMCs; TPC1 knockdown could significantly attenuate how NAADP promoted the proliferation of PASMCs (Figure 5A,B); it was further confirmed that TPC1 could inhibit Ca2+ signalling in PASMCs and PASMC proliferation to prove PAH, but caused no noticeable change in PASMC proliferation alone.