cel-mir-238: Cel-mir-238 is a synthesized C. elegans miRNA that was used as an internal calibrator in a study involving plasma samples [PMC5609864]. It was one of three miRNAs, along with cel-miR-39 and cel-miR-54, that were spiked into the samples [PMC5609864]. The purpose of using cel-mir-238 as an internal calibrator was to calculate the relative expression level of target miRNAs in the samples [PMC4014722]. The relative expression level was determined by calculating the difference in CT values between the target miRNA and cel-mir-238 [PMC4014722]. This calculation allowed for the quantification and comparison of target miRNA expression levels [PMC4014722]. The use of cel-mir-238 as an internal calibrator is a common practice in qRT-PCR experiments to ensure accurate and reliable measurements [PMC5609864]. By using synthesized C. elegans miRNAs like cel-mir-238, researchers can control for experimental variability and normalize their data [PMC5609864]. This approach allows for more accurate interpretation of qRT-PCR results and facilitates comparisons between different samples or experimental conditions [PMC5609864].