Updated publication reference for PubMed record(s): 29408197. Long non-coding RNAs (lncRNA) are transcribed but not translated ribonucleic acids with various functions. We analyzed a so far unreported lncRNA n342419, which we named MANTIS. A search for micropeptides after overexpression of MANTIS in Human Umbilical Vein Endothelial Cells (HUVEC) with subsequent LC-MS/MS without trypsination showed that none of the micropeptides found had any similarity to potential MANTIS ORFs, whereas the positive control yielded micropeptides encoded from GFP plasmid.