HOTAIR and neoplasm: The expression level of HOTAIR in tumor tissues from siRNA/HOTAIR-transfected A549/DDP cells was significantly lower than that in tumor tissues from siRNA/control-transfected cells, while the expression of p21 protein in tumor tissues from siRNA/HOTAIR1-transfected cells were higher than that in tumor tissues from siRNA/control-transfected cells (P<0.05; Figure 6C).