SLC2A4 and Insulin resistance: Over-expressed MKK6/3-p38/MAPK in L6 myotubes was reported to deteriorate the action of GLUT4 via down-regulation of GLUT4 gene expression [45], whereas knock-down MAP4K4, the upstream kinase of ERK1/2 and JNK, inhibits TNF-α-induced insulin resistance [46].