IGF1 and glioblastoma: Lei et al. (2017) have shown roles of miR-338-5p in suppressing the proliferation and migration of glioblastoma cells through the inhibition of EFEMP1, a regulator of matrix metalloproteinases [93], and Nielsen et al. (2014) observed an up-regulation of miR-338-3p in circulation after 1 h of acute exercise [94], allowing us to draw a parallel with the pro-growth effect of IGF1.