The following primary antibodies were used: rabbit anti-DsRed (Invitrogen, Carlsbad, CA), rabbit anti-tRFP (Evrogen, Moscow, Russia), chicken anti-GFP (Abcam, Cambridge, United Kingdom), rabbit anti-Mef2 (Santa Cruz Biotechnology, Dallas, TX), mouse anti-myosin heavy chain (Clone F59; Developmental Studies Hybridoma Bank, Iowa City, IA), mouse anti-PCNA (Sigma-Aldrich, St. Louis, MO), and rabbit anti-zf Raldh2 (Abmart, Berkeley Heights, NJ). The following secondary antibodies were used: Alexa Fluor 488 donkey anti-mouse IgG(H + L), Alexa Fluor 488 donkey anti-rabbit IgG(H + L), Alexa Fluor 555 donkey anti-mouse IgG(H + L), and Alexa 24 Fluor 555 donkey anti-rabbit IgG(H + L) (Invitrogen, Carlsbad, CA).