FOXI1 and neoplasm: ,12, 13, 14, 15, 16 However, these tumours share some molecular features including increased oxidative phosphorylation with upregulation of PPARG coactivator 1 alpha (PPARGC1a), an important co-activator for mitochondrial metabolism, as well as increased forkhead box I1 (FOXI1) expression, a transcription factor critical for collecting duct differentiation, suggesting that these shared molecular features may lead to similar histologies in these genetically different tumours.5