May be involved in transmitting sphingosine-1 phosphate (SPP)-mediated signaling into the cell (PubMed:12077123). Plays a role in the recruitment of PRDX3 to early endosomes (PubMed:15750338). . This is the function of ENSG00000136643 (RPS6KC1, ribosomal protein S6 kinase C1).