The myc2 myc3 myc4 (myc234) triple mutant was almost completely devoid of GSL and was extremely susceptible to the generalist herbivore Spodoptera littoralis. On the contrary the specialist Pieris brassicae was unaffected by the presence of GSL and preferred to feed on wild-type plants. In addition lack of GSL in myc234 drastically modified S. littoralis feeding behavior. Surprisingly the expression of MYB factors known to regulate GS biosynthesis genes was not altered in myc234; suggesting that MYC2/MYC3/MYC4 are necessary for direct transcriptional activation of GS biosynthesis genes. Yeast two-hybrid and pull-down experiments indicated that MYC2/MYC3/MYC4 interact directly with GS-related MYBs. This specific MYC–MYB interaction plays a crucial role in the regulation of defense secondary metabolite production and underlines the importance of GSL in shaping plant interactions with adapted and nonadapted herbivores (Schweizer et al. 2013)