NKD2 and gastric cancer: The knockdown of ZFAS1 enhanced the sensitivity of GC cells to PTX and cis-platinum by inactivating the Wnt/β-catenin signaling pathway via downregulating β-catenin and phosphorylated glycogen synthase kinase-3β (p-GSK3β) level and increasing naked cuticle homolog 2 (NKD2) expression.