[10] Human Drosha was cloned in 2000 when it was identified as a nuclear dsRNA ribonuclease involved in the processing of ribosomal RNA precursors.

[10] Members of the ribonuclease III superfamily of double-stranded (ds) RNA-specific endoribonucleases participate in diverse RNA maturation and decay pathways in eukaryotic and prokaryotic cells.

[12] The RNase III Drosha is the core nuclease that executes the initiation step of microRNA (miRNA) processing in the nucleus.

[16] A 2nt 3' overhang is generated by Drosha in the nucleus recognized by Dicer in the cytoplasm, which couples the upstream and downstream processing events.

[9] Both Drosha and Dicer can function as master regulators of miRNA processing and have been observed to be down-regulated in some types of breast cancer.

[18] However, the exact nature of the association between microRNA processing and tumorigenesis is unclear,[21] but its function can be effectively examined by siRNA knockdown based on an independent validation.

This can be shown by the knockdown of two important miRNA processing proteins, Drosha and Dicer, which leads to a significant enhancement of viral replication in PBMCs from HIV-1-infected patients.