MALAT1 and cancer: Most studies in the field of molecular mechanisms have reported that MALAT1 regulates tumor progression and metastasis through the following: 1) MALAT1 serves a competitive endogenous RNA that contains many putative binding sites of miRNAs; 2) MALAT1 interacts with Polycomb repressive complex 2 (PRC2) which catalyzes histone H3K27 methylation, which plays important roles in transcriptional repression and cancer; 3) signaling pathways including PI3K-AKT, MAPK, WNT, and NF-κB have been reported to be regulated by MALAT1 in cancer (45-47).