Zhang T, et al. - The association of donor and recipient small ubiquitin-like modifier 4 (SUMO4) rs237025 polymorphisms with tacrolimus elimination and the potential mechanism was investigated in this study. In the early period after liver transplant (LT), donor SUMO4 rs237025 genetic variant was associated with higher Tac C/D ratios, which could be related to the down-regulation of the CYP3A5 enzyme through the nuclear factor-κB (NF-κB) signaling pathway.