MicroRNAs appear to be tissue-specific and developmental-specific

Titrate the levels of key regulatory proteins → important in early development, cell proliferation, cell death and neurodevelopment. Dicer is deliberately disrupted in fertilised eggs → block the generation of all miRNAs at this developmental stage. If Dicer is deliberately inactivated in development in specific tissues, severe growth defects are seen → miRNAs are able to fine tune protein levels