Indeed, small RNA-Seq analyses in 8 CRC cell lines revealed that a low percentage of piRNAs (<7%) is detectable in all cases, independently from the expression patterns of PIWIL genes, a result supported by gene knock-down experiments in somatic tissues that demonstrated how PIWIL1 depletion does not significantly affect piRNA levels [50,51]. The gene discussed is PIWIL1; the disease is colorectal carcinoma.