Microtubules are dynamic cytoskeletal structures essential for shaping cellular architecture and driving cell motility. Their tube-like structure typically comprises 13 protofilaments, each of which is formed of α/β tubulin heterodimers arranged in a head-to-tail manner (Howard, 2001). The formation of microtubules primarily contains two processes. The first process in which soluble dimers start to form a growing microtubule is termed microtubule nucleation (Figure 1A). Spontaneous nucleation, i.e. de novo microtubule formation from free dimers, is thermodynamically unfavorable, so cellular microtubules usually nucleate from existing templates (i.e. microtubule organization centers, MTOCs) (Wieczorek et al., 2015) (Figure 1A). The distribution of MTOCs (e.g. the γ-tubulin ring complex) shapes the organization of cytoplasmic microtubules in cells. The rate of nucleation can be regulated by protein molecules associated with MTOCs or involved in microtubule assembly (Wieczorek et al., 2015). In the second process, microtubules show persistent growth but occasionally switch from a relatively slow elongation phase to a rapid shortening phase (i.e. catastrophe) and then switch back (i.e. rescue) (Figure 1A). This behavior is known as microtubule dynamic instability (Mitchison and Kirschner, 1984), which is regulated by microtubule-associated proteins. The mean length (Lmean) of cellular microtubules can be estimated by the parameters that describe microtubule dynamic instability (Eq. 1):