(A) The regulatory relationship between lin-4 and lin-14, as defined by the discoveries of Ambros and Ruvkun, highlighting the seven complementary binding sites of lin-4 on the 3′ UTR of lin-14. (B) The evolutionary conservation of let-7 sequences is displayed across key model organisms, including Caenorhabditis elegans, Drosophila melanogaster, mice (Mus musculus), and humans (Homo sapiens). (C) MicroRNAs at the intersection of cancer hallmarks, highlighting their involvement in processes such as immune evasion, angiogenesis, metastasis, and cellular proliferation. While significant progress has been made in understanding their roles, many aspects remain undefined, emphasizing the need for further research into their complex contributions to tumor biology and cancer progression.