PIK3CA and osteosarcoma: lncRNA TUG1 promoted the proliferation, migration, and invasion of osteosarcoma through competitively sponging of miR-219a-5p, resulting in the up-regulation of phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and the activation of the protein kinase B (AKT) signal pathway (Yang et al. 2018a).