NOX4 and neoplasm: Neither any of the known cytosolic oxidase proteins nor the GTPase Rac are required for its activity, which appears to be regulated mainly at the transcriptional level.38, 39, 40 Role of NOX4 in tumour progression is controversial and recent studies propose a role for NOX4 in supporting tumour migration.41, 42 However, although most of these studies were performed in two-dimensional migration systems, we have analysed the role of NOX4 in 3D systems that recapitulate interstitial tissue surrounding tumours, where we previously found that amoeboid migration is particularly efficient.