EpoY (SD-142) is an irreversible inhibitor of the primary brain microtubule-associated tyrosine carboxypeptidase (TCP), a complex formed by vasohibin-1 (VASH1) and small vasohibin-binding protein (SVBP). By inhibiting TCP with an IC50 value of approximately 500 nM, EpoY effectively reduces the levels of detyrosinated α-tubulin, which is crucial for microtubule dynamics and neuronal differentiation. This inhibition results in significant differentiation defects and is linked to potential issues related to cancer and cardiomyopathy.