This is consequential to the fact that while GLUT4 is mainly expressed in muscle and fat tissues and exquisitely regulated by insulin [105], GLUT1 is ubiquitously expressed in cells and tissues [106] and is not regulated by insulin but induced by hypoxia at the transcriptional level [107,108] and is overexpressed in cancer [109,110,111,112]. This evidence concerns the gene SLC2A4 and cancer.