Involved in the cytoplasmic maturation steps of pre-60S ribosomal particles by promoting the release of shuttling protein RSL24D1/RLP24 from the pre-ribosomal particles. Acts together with SPATA5, SPATA5L1 and CINP. Interacts with SPATA5, SPATA5L1 and CINP. Does not associate with pre-60S ribosomal particles. Phosphorylated on serines by CK2 kinase.