In contrast, flexing resulted in a significant increase in CKM, LDH, TNNT2 and TNNI3 levels in media from DMD hiPSC-CMs compared to those in media from healthy control hiPSC-CMs, mirroring what is seen clinically in serum from patients with DMD. The gene discussed is TNNT2; the disease is Duchenne muscular dystrophy.