“…Excellent reviews of the yeast CWI pathway and the extent of its influence on yeast physiology have been published [ 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 ]. Sc PRS mutant strains have consistently shown varying degrees of sensitivity to the purine analogue, caffeine (1,3,7-tri-methylxanthine), thus compromising CWI signalling via the MAPK (mitogen-activated protein kinase) [ 64 , 74 , 79 , 82 , 92 ]. It should be noted that caffeine not only interferes with the integrity of the cell wall, but also possibly by the inhibition of mTOR (mechanistic Target Of Rapamycin) mTORC1 and mTORC2, well-known regulators of eukaryotic cellular metabolism [ 93 , 94 , 95 ].…”