cel-mir-2: Cel-mir-2 is a Caenorhabditis elegans miRNA that was used as a negative control in several experiments [PMC1874652] [PMC1292995] [PMC7801652] [PMC3465266] [PMC2649537] [PMC7290581] [PMC2383925]. It did not produce a detectable signal in these experiments, even when high concentrations of RNA were used [PMC1292995]. Cel-mir-2 was absent from most of the samples, and therefore, cel-lin-4 was used for normalization instead [PMC7801652]. Cel-mir-2 is closely related to bma-miR-2a and is 100% identical to it [PMC4019659]. It was added at a lower concentration compared to cel-miR-76 in an experiment, and the difference in their ΔCq values was used to account for differences in PCR efficiency between the two assays [PMC6414634]. Cel-mir-2, along with ath-miR-159a and cel-lin-4, were negative controls that showed no expression in human tissue samples and were used to assign Ct cut-off values for miRNA detection assays as absent calls for each miRNA tested. Positive controls such as miR-16 and let-7a were also used for this purpose. In an experiment involving milk-derived miRNAs, cel-mir-2 exhibited sharp degradation when subjected to prolonged incubation at 37 °C or low pH or treated with high concentrations of exogenous RNase. However, endogenous milk-derived miRNAs showed resistance to degradation under these conditions.