PHOX2B and Respiratory insufficiency due to muscle weakness: The loss of RTN neurons leads to respiratory depression in vivo and in vitro, and RTN Phox2b neurons have been a leading candidate for an independent respiratory oscillator driving abdominal and, possibly, VII motor output (Onimaru et al., 2008; Thoby-Brisson et al., 2009; Feldman et al., 2013).