D’Arrigo et al. (2017) and Tufano et al. (2021) showed that FKBP51s enhance PD-L1 surface expression via protein folding and glycosylation processes. This regulation is critical because PD-L1 is pivotal for reducing the host’s antitumor immunity. Interestingly, Yamaguchi et al. (2020) found that celecoxib downregulates PD-L1 in glioma cells by modulating FKBP51 post-transcriptionally. Tufano et al. (2021) further suggested that FKBP51s may coordinate PD-L1 expression with cell cycle progression via cyclin D, suggesting a complex regulatory axis that deserves deeper exploration. This evidence concerns the gene FKBP4 and glioma.