MicroRNA miR-19b, encoded by two genomic loci, MIR19B1 and MIR19B2, is homologous to miR-19a and also binds to the 3'UTR of PTEN mRNA (Polseno, Salmena, Zhang et al. 2010). miR-19b microRNA causes reduction in both PTEN mRNA and protein levels and is thus shown to function as a part of the endonucleolytic RISC. It is possible that miR-19b microRNA also functions as a part of the nonendonucleolytic RISC.
