A model for aryl hydrocarbon receptor (AHR) pathway attenuation by RNA-binding protein Musashi-2 (MSI2) post-transcriptional processing. MSI2 mediates the posttranscriptional downregulation of HSP90 at the outset of culture and continuously represses the prominent AHR pathway effector CYP1B1 to facilitate haematopoietic stem and progenitor cell (HSPC) expansion. The resulting MSI2-mediated repression of AHR signalling enforces a self-renewal program and allows HSPC expansion ex vivo. Reprinted by permission from Macmillan Publishers Ltd: Nature, Rentas et al, Vol. 532 Pages 508-511, 2016.