en Genetics Review Article <div style="text-align: justify;"><span style="font-family:Times New Roman;">MiR-21 is a critical small regulatory RNA involved in various cellular processes such as cell cycle, apoptosis, migration, and differentiation of stem cells. It is significantly upregulated in CRC cell lines and tissue samples, acting as a biomarker and playing an important role in the pathogenesis of CRC. MiR-21 targets and downregulates tumor suppressor genes such as PDCD4, which are part of the PI3K- mTOR pathway. The inverse relationship between miR-21 and PDCD4 expression highlights the miR-21 role in CRC progression. Research shows that miR-21 is upregulated in human CRC cell lines and tissue samples, correlating with advanced clinical stages, lymph node metastasis, and poor prognosis. This regulation highlights the potential of miR-21 as a biomarker for the early detection of CRC and as a therapeutic target for developing targeted therapies. MiR-21 regulates several CRC-related target genes, highlighting its role in cancer initiation, transformation, invasion, and metastasis. These findings provide valuable insights into miR-21&#39;s role in cancer pathogenesis and its potential clinical applications.</span></div> Colorectal Cancer, miR-21, miRNA, Oncogenic, genetics factor 0 0 http://mcijournal.com/browse.php?a_code=A-10-691-1&slc_lang=en&sid=1 Mohammad Kordkatouli mohammad.kordkatouli@outlook.com 10031947532846004062 0009-0006-3008-6820 No Department of Biology, Gorgan Branch, Islamic Azad University, Gorgan, Iran Seyed abolghassem Mohammadi bondarkhilli sambondar2@gmail.com 10031947532846004063 0009-0004-1724-5298 Yes Department of Biology, Gorgan Branch, Islamic Azad University, Gorgan, Iran Aryan Sateei Aryan.Sateei@iau.ac.ir 10031947532846004064 10031947532846004064 No Department of Biology, Gorgan Branch, Islamic Azad University, Gorgan, Iran Mehr Ali Mahmood Janlou mehr.janlou@gmail.com 10031947532846004065 10031947532846004065 No Department of Biology, Gorgan Branch, Islamic Azad University, Gorgan, Iran