KRAS and neoplasm: Regarding benign tumour tissues, Shahrabi-Farahani and colleagues reported that during the proliferative phase of the menstrual cycle, K-RAS4A mRNA was upregulated (2.7-fold higher) in eutopic endometrium in patients with endometriosis compared to controls (Shahrabi-Farahani et al., 2015), whereas no significant correlation was observed between K-RAS4B and the different menstrual cycle phases (Farahani et al., 2015).