Fig. 5

a Strategy for confirmatory assay for the cardiogenic activity of novel compounds. Compounds were added either prior to (D6–D8, cardiac progenitors) or after (D7–D9, cardiomyocytes) the onset of spontaneous beating in defined, serum-free conditions. b venGFP total fluorescence upon compound treatment with 3i-1000, 3i-1103, and 3i-1047. Cardiac progenitor (CP) and venGFP (Myl2-eGFP, ventricular). Data is presented as mean ± SEM (n = 4, independent experiments). *P < 0.05 (T test vs DMSO control)