Figure 2.

Sources of microRNAs (miRNAs) in body fluids for lung cancer biomarker discovery. miRNAs have been obtained from peripheral-blood-derived samples, bronchoalveolar lavage fluid, pleural effusion, pleural lavage fluid, and sputum of lung cancer patients. Available identification and quantification technologies include microarrays, next-generation sequencing, and real-time quantitative PCR (qPCR). Each technology requires the extraction of RNA from the biological fluid and the synthesis of complementary DNA (cDNA) by reverse transcription (RT).