RAC1 and cancer: The relevance of APA in cancer was established with the discovery of a systemic increase in the usage of a proximal PAS leading to consistently shortened 3′ UTRs of oncogenes such as insulin like growth factor 2 mRNA binding protein 1 (IGF2BP1), Rac family small GTPase 1 (RAC1), and cyclin D2 (CCND2) (Mayr and Bartel 2009; Chen et al. 2018b).