Only the Mef2c-Gata4-Tbx5 (MGT) and Mef2c-Tbx5-Gata4 (MTG) constructs, which have Mef2c in the first position, increase reprogramming efficiency compared to infection with three separate Gata4, Mef2c, and Tbx5 viruses (Wang et al., 2015a). Here, TBX5 is linked to infection.