METTL3 and urinary bladder cancer: As an important m6A regulator enzyme, the methyltransferase, METTL3, can promote tumor progression by regulating downstream target genes in leukemia [29], colorectal cancer [30, 31], bladder cancer [32], and gastric cancer [33]; however, the relationship between the m6A writer, METTL3, and VM formation remains unclear.