FOXP3 and Autoimmunity: Here, we show that DDX39B controls expression of gene products involved in autoimmunity including Forkhead Box P3 (FOXP3), a master regulator of the development, maintenance and function of CD4+/CD25+ regulatory Tcells (Tregs; Georgiev et al., 2019; Hori, 2021; Josefowicz et al., 2012), and a repressor of autoimmune diseases (Bennett et al., 2001; Brunkow et al., 2001; Chatila et al., 2000; Wildin et al., 2001).