Several studies have evaluated the potential roles of ROS generation in angiogenesis and tumour growth, and reported that ROS generation could induce the activation of mitogen-activated protein kinase, nuclear factor-κB, activator protein 1, and VEGF production, all of which are strongly associated with tumour development (Schreck et al, 1992; Stevenson et al, 1994; Puri et al, 1995), although the role of ROS generation in cancer cells remains controversial, because it also increases pro-apoptotic molecules such as p53 and p38 mitogen-activated protein kinase (Lee, 1998; Lau et al, 2010). This evidence concerns the gene WNK2 and neoplasm.