SLC2A1 and cancer: Consistently, there was reduction or elevation in promoter activity, transcript levels, or protein expression of GALNT6 and MGAT1 in cancer cells stably transfected with circ-hnRNPU or sh-circ-hnRNPU #1, along with altered expression of downstream O-glycosylated proteins FN1 [29] and GLUT1 [30], which were abolished by ectopic expression or knockdown of NONO or c-Myc (Fig. 5c, d, Additional file 1: Fig. S4e-g).