Editing G1 phase (section)

==In cancer==

{{Main|Cell cycle#Role in tumor formation|l1=Cell cycle role in cancer}}

Many sources have linked irregularities in the G<sub>1</sub> phase or the G<sub>1</sub>/S checkpoint to uncontrolled growth of [[tumors]]. In these cases where the G<sub>1</sub> phase is affected, it is generally because [[Regulation of gene expression|gene regulatory proteins]] of the [[E2F]] family have become unrestrained and increase G<sub>1</sub>/S cyclin gene expression, leading to uncontrolled cell-cycle entry.<ref name=Morgan />

However, the cure for some forms of cancer also lies in the G<sub>1</sub> phase of the cell cycle. Many cancers including [[breast cancer|breast]]<ref>{{cite journal | vauthors = Wali VB, Bachawal SV, Sylvester PW | title = Combined treatment of gamma-tocotrienol with statins induce mammary tumor cell cycle arrest in G1 | journal = Experimental Biology and Medicine | volume = 234 | issue = 6 | pages = 639–50 | date = June 2009 | pmid = 19359655 | doi = 10.3181/0810-RM-300 | s2cid = 30323288 }}</ref> and [[skin cancer|skin]] cancers <ref>{{cite journal | vauthors = Ye Y, Wang H, Chu JH, Chou GX, Chen SB, Mo H, Fong WF, Yu ZL | title = Atractylenolide II induces G1 cell-cycle arrest and apoptosis in B16 melanoma cells | journal = Journal of Ethnopharmacology | volume = 136 | issue = 1 | pages = 279–82 | date = June 2011 | pmid = 21524699 | doi = 10.1016/j.jep.2011.04.020 }}</ref> have been prevented from proliferating by causing the tumor cells to enter G<sub>1</sub> cell cycle arrest, preventing the cells from dividing and spreading.