Myogenin have a short half-life of between 20 and 60 min (Edmondson et al. 1991; Viñals et al. 2004).
Edmondson DG, Brennan TJ, Olson EN. Mitogenic repression of myogenin autoregulation. Journal of Biological Chemistry 1991;266(32):21343-6. http://www.jbc.org/content/266/32/21343.full.pdf
Viñals F, Ventura F. Myogenin protein stability is decreased by BMP-2 through a mechanism implicating Id1. Journal of Biological Chemistry 2004;279(44):45766-72. http://www.jbc.org/content/279/44/45766.full.pdf
For the half-life of blood iris see the following article:
Saleh BO, Majeed MJ, Oreaby GM. Irisin impact as a medication that ameliorate and hinder the development of insulin resistance associated disorders without regular exercise (experimental study). IOSR Journal of Dental and Medical Sciences 2014;13(9):28-35. http://www.iosrjournals.org/iosr-jdms/papers/Vol13-issue9/Version-3/H013932835.pdf