Total RNA yield from different kits was measured with Ribogreen RNA assay (A).The recovery of mRNAs of 3 reference genes (GAPDH, ACTB, and RPS9) from different kits was determined with RT-qPCR (B). The Ct valures of each gene from different kits were plotted. Recovery of miRNAs (miR148a, miR21, and miR26a) (C) and piRNAs (piR-001184, piR-014923, and piR-01857) (D) of each isolation kit was measured with droplet digital PCR(ddPCR) method. The relative yield of each small RNA was normalized by setting the highest mean copy number from 1 kit as 100%.