HIF1A and colorectal cancer: Further examples include a hypoxia-induced HIF1α-circTDRD3 positive loop that exacerbates colorectal cancer growth and metastasis [23], and a positive feedback loop between EBP2 and c-Myc that contributes to regulating rDNA transcription, cell proliferation, and tumorigenesis [24], whereas comprehensively mapped feedback loops between LncRNA PTENP1 and miR-21/PTEN have been implicated in the regulation of epithelial–mesenchymal transition and drug resistance in NSCLC [25].