As a result of the development of PI3K inhibitors, there has been an increased interest in investigating the resistance mechanisms to PI3K inhibitors in the context of breast cancer, and several studies have been done in this direction (Costa et al., 2015; Castel et al., 2016; Toska et al., 2017; Bosch et al., 2015; Elkabets et al., 2013; Le et al., 2016; Vora et al., 2014; Kodack et al., 2017; Zwang et al., 2017). Here, PIK3CA is linked to breast cancer.