The miR-34 family plays a critical role in cancer and apoptosis, acting as direct targets of the tumor suppressor p53. miR-34a and miR-34b/c are induced by p53 and promote apoptosis, cell-cycle arrest, or senescence. In many cancers, these miRNAs are inactivated by CpG methylation, leading to resistance to apoptosis. The miR-34 family is involved in tumor suppression by downregulating oncogenes and anti-apoptotic proteins. miR-34a is located on 1p36 and is commonly deleted in neuroblastomas. Its loss is associated with resistance to chemotherapy. miR-34a and miR-34b/c are also involved in cell-cycle regulation and apoptosis. miR-34a targets SIRT1, leading to increased p53 activity and apoptosis. miR-34a also targets Bcl-2, reducing anti-apoptotic effects. miR-34a can feed back to p53, enhancing its activity. In cancer, miR-34 inactivation is linked to tumor progression. miR-34 expression is often reduced in various cancers due to mutations in p53 or epigenetic changes. miR-34a is a potential biomarker for cancer diagnosis and prognosis. Therapeutic strategies targeting miR-34, such as using miR-34 agonists, may help overcome chemotherapy resistance. miR-34 is also involved in cellular senescence and aging. The miR-34 family's role in cancer is complex, involving multiple pathways and interactions with other regulatory molecules. Understanding miR-34's functions in cancer could lead to new therapeutic approaches.The miR-34 family plays a critical role in cancer and apoptosis, acting as direct targets of the tumor suppressor p53. miR-34a and miR-34b/c are induced by p53 and promote apoptosis, cell-cycle arrest, or senescence. In many cancers, these miRNAs are inactivated by CpG methylation, leading to resistance to apoptosis. The miR-34 family is involved in tumor suppression by downregulating oncogenes and anti-apoptotic proteins. miR-34a is located on 1p36 and is commonly deleted in neuroblastomas. Its loss is associated with resistance to chemotherapy. miR-34a and miR-34b/c are also involved in cell-cycle regulation and apoptosis. miR-34a targets SIRT1, leading to increased p53 activity and apoptosis. miR-34a also targets Bcl-2, reducing anti-apoptotic effects. miR-34a can feed back to p53, enhancing its activity. In cancer, miR-34 inactivation is linked to tumor progression. miR-34 expression is often reduced in various cancers due to mutations in p53 or epigenetic changes. miR-34a is a potential biomarker for cancer diagnosis and prognosis. Therapeutic strategies targeting miR-34, such as using miR-34 agonists, may help overcome chemotherapy resistance. miR-34 is also involved in cellular senescence and aging. The miR-34 family's role in cancer is complex, involving multiple pathways and interactions with other regulatory molecules. Understanding miR-34's functions in cancer could lead to new therapeutic approaches.