RPS6KB1 and cancer: Ribosomal protein S6 kinase beta-1 (S6K1) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) are well-known downstream targets of mTOR signaling pathway that regulate ribosome RNA biogenesis and protein synthesis, therefore functioning as a critical regulator in tumor cell proliferation, motility, invasion and cancer metastasis [13,14].