Upon phosphorylation by the protein tyrosine kinase from activated T cells after organ transplantation, hydrogelators in the tacrolimus‐coassembled nanofibers will be efficiently converted to their hydrophilic phosphates, resulting in the disassembly of the nanofibers and the release of tacrolimus for T‐cell inhibition. This is reported by Jindao Wu, Zhen Zheng, Yuanyuan Chong, Xiangcheng Li, Liyong Pu, Qiyun Tang, Liu Yang, Xuehao Wang, Fuqiang Wang, and Gaolin Liang in the article https://doi.org/10.1002/adma.201805018. To know more, please go to the Advanced Materials homepage.