PRODH and cancer: A microarray analysis of iBAT from Alk7-/- global knock-out mice revealed several changes in gene expression in mutant iBAT compared to wild type controls (Figure 3—figure supplement 1A,B), including upregulation in the level of Prodh mRNA, encoding proline dehydrogenase (POX), a mitochondrial enzyme that catalyzes the first step in the degradation of proline, and a critical component of metabolic responses to nutrient stress in cancer cells (Pandhare et al., 2009; Phang, 2019).