MicroRNAs are small noncoding RNAs that function to control gene expression. 
These small RNAs have been shown to contribute to the control of cell growth, 
differentiation and apoptosis, important features related to cancer development 
and progression. In fact, recent studies have shown the utility of microRNAs as 
cancer-related biomarkers. This is due to the finding that microRNAs display 
altered expression profiles in cancers versus normal tissue. In addition, 
microRNAs have been associated with cancer progression. In this review, the 
mechanisms to alter microRNA expression and their relation to cancer will be 
addressed. Moreover, the potential application of microRNAs in clinical settings 
will also be highlighted. Finally, the challenges regarding the translation of 
research involving microRNAs to the clinical realm will be discussed.