STAT3 and neoplasm: Oncogenic signaling pathways, such as c-Myc, Ras, high-mobility group A (HMGA), and signal transducer and activator of transcription 3 (STAT3), which are critical in tumorigenesis, proliferation and invasion, are targeted by let-7 and, thus, let-7 is associated with stem cell differentiation and tumor suppression [39,40,41,42].