CCND1 and cancer: Regarding the translational control of cyclin D1, mammalian target of rapamycin complex 1 (mTORC1) signaling is known to promote the translation of cyclin D1 mRNA.17, 18, 19 The protein stability of cyclin D1 is then mainly regulated via the ubiquitin proteasome system.20, 21, 22 Thus the expression of cyclin D1 is pleiotropically regulated in the progression of cancer.