HMGA2 and neoplasm: Considering that let-7 miRNA family functions mainly as tumor suppressor genes [30] to target oncogenes such as RAS and high mobility group A2 (HMGA2) [31], we propose that AZ-P7a cells selectively secrete let-7 miRNAs into the extracellular environment via exosomes to maintain their tumorigenic and metastatic propensities.