MTCL1 (microtubule crosslinking factor 1) is a microtubule-associated protein that plays crucial roles in both interphase and mitotic cellular functions. The protein functions as a parallel dimer through multiple coiled-coil domains and crosslinks microtubules via its N-terminal microtubule-binding domain while stabilizing them through its C-terminal domain 1. During interphase, MTCL1 is recruited to Golgi membranes through interactions with CLASPs and AKAP450/CG-NAP, where it promotes microtubule growth and formation of stable perinuclear microtubule networks essential for Golgi ribbon formation 2. In polarized epithelial cells, MTCL1 contributes to the development and maintenance of non-centrosomal microtubule bundles at lateral membranes 1. During mitosis, MTCL1 functions as a CLASP-interacting protein that localizes to spindle microtubules, spindle poles, and kinetochores, playing essential roles in faithful chromosome 18 3. Clinical significance includes its potential role in cerebellar ataxia, as a homozygous loss-of-function variant was identified in a patient with progressive cerebellar ataxia, and MTCL1 is highly expressed in cerebellar Purkinje cells 4. Additionally, circular RNA forms of MTCL1 have been implicated in various pathological conditions including laryngeal squamous cell carcinoma and Hirschsprung's disease 56.