biostudies-literatureUnknownCassidy ACNEI NIH HHSNIDDK NIH HHSNCI NIH HHSNIGMS NIH HHSMicrotubule dynamics change during cell division to enable rapid microtubule network remodeling. The switching from microtubule growth to shrinkage is attributed to the loss of a stabilizing GTP-cap structure at the growing microtubule end. The size of the GTP-cap is a result of a balance between GTP-tubulin addition to the microtubule end and subsequent GTP-hydrolysis in the microtubule lattice. Whether the cell-cycle-dependent changes in microtubule dynamics are supported by concurrent modulation of the stabilizing GTP-cap size is not known. Here, we use high spatiotemporal resolution live-cell imaging of EB1, an established marker for the GTP-cap, to directly determine the relationship between GTP-cap size and microtubule growth rate throughout the cell cycle. Our data reveal that GTP-cbioRxiv : the preprint server for biology2026.01.13.699367https://www.ebi.ac.uk/biostudies/studies/S-EPMC12871301biostudies-literatureThe microtubule GTP-tubulin cap size is modulated during cell division.PMC12871301P30 CA068485R35 GM125028P30 DK058404P30 EY008126R35 GM119552Zanic MBurnette DTCassidy ACfalseThe microtubule GTP-tubulin cap size is modulated during cell division.Microtubule dynamics change during cell division to enable rapid microtubule network remodeling. The switching from microtubule growth to shrinkage is attributed to the loss of a stabilizing GTP-cap structure at the growing microtubule end. The size of the GTP-cap is a result of a balance between GTP-tubulin addition to the microtubule end and subsequent GTP-hydrolysis in the microtubule lattice. Whether the cell-cycle-dependent changes in microtubule dynamics are supported by concurrent modulation of the stabilizing GTP-cap size is not known. Here, we use high spatiotemporal resolution live-cell imaging of EB1, an established marker for the GTP-cap, to directly determine the relationship between GTP-cap size and microtubule growth rate throughout the cell cycle. Our data reveal that GTP-c2026-01-01T00:00:00Z2026 Jan2026-07-06T03:17:58.423Z2026-07-06T03:11:41.171ZS-EPMC128713014164812210.64898/2026.01.13.699367