Epithelial Cell Transforming Sequence 2 (Ect2) is a guanine nucleotide exchange factor (GEF) that catalyses the exchange of GDP for GTP. Like other GEFs, Ect2 serves as molecular switches in diverse signaling pathways, including cell polarity, mitotic spindle assembly, cytokinesis, etc [, , ]. Ect2 interacts with several members of the Rho GTPase family including, RhoA, RhoB, RhoC, RhoG, Rac1 and Cdc42 [, , , , ]. Ect2 regulates the formation of the actomyosin contractile ring at mitotic exit through activation of RhoA and functions in metaphase for the process of spindle assembly through activation of Cdc42 []. Ect2 is regulated through a number of mechanisms including phosphorylation, intracellular localization and intra- and inter-molecular interactions []. Ect2 is established as a human oncogene []. It is highly expressed in a variety of human tumors including brain lung, bladder, esophageal, pancreatic and ovarian tumors [, , , , ]. Ect2 is also suggested to play a role in neuronal differentiation and brain development [].
PRC1 is a microtubule binding and bundling protein essential to maintain the mitotic spindle midzone []. It is a key regulator of cytokinesis that cross-links antiparallel microtubules at an average distance of 35 nM [, ]. PRC1 is also required for KIF14 (a kinesin-3 family motor protein) localisation to the central spindle and midbody [, , ]and is required to recruit PLK1 to the spindle. It stimulates PLK1 phosphorylation of RACGAP1/HsCyk-4 to allow recruitment of ECT2 to the central spindle [].
This is a family of microtubule associated proteins, including MAP65 (MAP65-1/2/3/4/5/6/7/8/9) from Arabidopsis, Ase1 from yeast, and PRC1 from mammals.Ase1 is required for spindle elongation and stabilisation. It is cell cycle-regulated by anaphase promoting complex []. It is a potential Cdc28p substrate []. MAP65-1 plays a role in stabilising anti-parallel microtubules in the central spindle at anaphase to early cytokinesis. MAP65-1 is cell cycle regulated by phosphorylation [, , , , ].PRC1 is a microtubule binding and bundling protein essential to maintain the mitotic spindle midzone []. It is a key regulator of cytokinesis that cross-links antiparallel microtubules at an average distance of 35 nM [, ]. PRC1 is also required for KIF14 (a kinesin-3 family motor protein) localisation to the central spindle and midbody [, , ]and is required to recruit PLK1 to the spindle. It stimulates PLK1 phosphorylation of RACGAP1/HsCyk-4 to allow recruitment of ECT2 to the central spindle [].
