Model for the role of Nle in hematopoietic cells. In HSCs/MPPs, Nle is absolutely required for proper 60S subunit biogenesis. In the absence of Nle, the pathway is impaired and the pre-60S subunit accumulates within the nucleus. In more committed progenitors and differentiated cells, an Nle-independent pathway is active and allows the production of the 60S subunit in absence of Nle.