Marc Kirschner recalls that the mid-1980s “was a very innovative time.” While the era was giving rise to stonewashed jeans and rap music, cell biology was entering new territory as it finally went molecular. For cell biologists who, like Kirschner, were interested in the cytoskeleton, there was an even more exciting possibility: the modification of interesting proteins to form reagents that could be used to follow dynamics inside of cells. Kirschner's attention turned specifically to biotinylated tubulin.
By 1986, in vitro experiments had given rise to several models for microtubule (MT) dynamics, most notably treadmilling at steady-state (Margolis and Wilson, 1978) or the unusual growing and shrinking MT behavior termed “dynamic instability” (Mitchison and Kirschner, 1984). In a few preliminary in vivo experiments, it appeared that interphase MTs exchanged tubulin subunits rapidly, on the order of every 20 min (Salmon et al., 1984; Saxton et...
