**6. Conclusions**

Transcriptomic, proteomic, and lipidomic studies, which have multiplied in the last few years, have confirmed and/or revealed the involvement of peroxisomal metabolism in various biological processes essential for cellular adaptation, brain homeostasis, or even immune response and inflammation. Peroxisomal ABC transporters constitute a pathway for the entry of various lipid substrates into the peroxisome mainly for their degradation but also for the synthesis of bioactive lipids impacting membranes and signaling pathways. It is therefore quite logical that the role of peroxisomal ABC transporters is now extended to unexpected biological processes. Since their cloning in the 90s, the lack of good antibodies, the rarity of relevant cell models, the fragility of the peroxisomal membrane, and other difficulties have constituted a real handicap towards performing functional assays and in vitro transport reconstitutions, and progressing in the understanding of the role of peroxisomal ABC transporters. The emergence of new cell models and the rise of model organisms, as well as cell reprogramming and CRISPR gene editing technologies, suggest that major new discoveries will be made soon that reveal their role in physiological and pathological situations.

**Author Contributions:** A.T., C.G., D.T., and S.S. contributed to the bibliography and writing equally. S.S. coordinated and finalized the elaboration of the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** The authors of this review received no external funding for this bibliographical work.

**Acknowledgments:** The authors acknowledge the French Ministère de l'Enseignement Supérieur, de la Recherche et de l'Innovation, the University of Bourgogne, as well as the NFRF-Exploration stream (NFRF-E-2019-00007) (Canada) for funding the current scientific projects of the Bio-PeroxIL laboratory.

**Conflicts of Interest:** The authors declare no conflict of interest.
