**9. Concluding Remarks**

Caffeine, one of the most consumed and widely accepted neurostimulants, is also a powerful agent used in life science research. Due to its pleiotropic effects [163], caffeine is an active modulator of different enzymes and their regulatory pathways, which include important molecular players such as TOR kinases or DNA damage checkpoint kinases. Many of the studies reviewed here, which made use of the interaction between caffeine and *S. cerevisiae,* contributed to elucidating molecular mechanisms involved in biologic processes of general concern, such as DNA repair mechanisms, cancer, or aging. Using various approaches and setting multiple targets, the studies on caffeine–*S. cerevisiae* interaction generated outputs which could be extrapolated to higher organisms. In spite of the pleiotropic effects of caffeine, there is one mechanism universally accepted, i.e., the inhibitory effect on PI3 kinases, including the core kinases from the TOR complexes. However, since many of the puzzle pieces are still missing, it is no doubt that the duo caffeine–*S. cerevisiae* has not yet reached its full potential in opening doors to new knowledge.

**Author Contributions:** Conceptualization, L.L.R. and I.C.F.; resources, L.L.R. and I.C.F.; data curation, L.L.R. and I.C.F; writing—original draft preparation, L.L.R; writing—review and editing, I.C.F.; visualization, L.L.R. and I.C.F.; supervision, L.L.R. and I.C.F.; project administration, L.L.R. and I.C.F.; funding acquisition, L.L.R. and I.C.F. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

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

### **References**


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