COL5A2 and glioma: Moreover, it has recently been independently detected by other studies in vivo or in vitro that the increased expression of COL5A2 in colorectal cancer [32], the increased expression of PTTG1 with correlation to poor prognosis in glioma [33], and the down-regulation of the PTGDS as an important variable in liver and bladder cancer cell and in malignant progression forms of oral tissue [34-36].