TNNI3 and pulmonary arterial hypertension: Control and PAH iPSC-CMs expressed early and late cardiac markers, such as cardiac transcription factors (NKX2.5, TBX5, MEF2A, MEF2C, and GATA4), structural genes (ACTN1, MYH6, MYH7, MYL2, MYL7, TNNI3, and TNNT2), and calcium-handling (ATP2A2 and CX43) genes (Figure 3A).