Actinin Animals Antineoplastic Agents Arsenicals Biomechanical Phenomena Blotting, Western Brachyury protein Cell Differentiation Cell Line Connexin 43 Fetal Proteins Fluorescent Antibody Technique GATA4 Transcription Factor Gene Expression Homeobox Protein Nkx-2.5 Homeodomain Proteins Mice Mouse Embryonic Stem Cells Myocytes, Cardiac Nkx2-5 protein, mouse Oxides Reverse Transcriptase Polymerase Chain Reaction Sarcomeres Spheroids, Cellular T box transcription factor T-Box Domain Proteins Time Factors Transcription Factors Troponin C Troponin T