BRAF and cancer: However, some class 2 BRAF alterations were reported to coexist with RAS alterations.7,8 In contrast, class 3 BRAF variants, defined as RAS dependent, can be found without coexisting RAS alterations.7,8 Variation coexistence analysis using cancer genomics database provides evidence for functional interactions between activated RAS and BRAF alterations, and thus can support in vivo RAS dependency or independency.