RRM2 and neoplasm: Many other ncRNAs have been shown to be altered in their expression, supporting tumor pathogenesis, such as miR-1 downregulation, which is associated with SCLC growth and metastasis through the regulation of the CXCR4/FOXM1/RRM2 axis [67], and lncRNA PROX1-AS1 upregulation, which acts as a tumor promoter [68].