Similarly, in rat-1 fibroblast and C6 glioma cells, inhibition of p38 MAPK with SB203580 lengthened the period of the PER2::LUC reporter [41], and inhibition of U2OS cells with SB202190 lengthened the period of a Bmal1-dLuc reporter [53]. Here, PER2 is linked to glioma.