Acts as a mediator between the cap-binding complex (CBC) and the primary microRNAs (miRNAs) processing machinery during cell proliferation. Contributes to the stability and delivery of capped primary miRNA transcripts to the primary miRNA processing complex, thereby playing a role in RNA-mediated gene silencing (RNAi) by miRNAs (By similarity). Independently of its activity on miRNAs, necessary and sufficient to promote neural stem cell self- renewal. Does so by directly binding SOX2 promoter and positively regulating its transcription (By similarity).