TP53 and neoplasm: The regression of the tumour xenografts was associated with senescence, because p16Ink4a mRNA expression was significantly elevated and the candidate senescence markers, such as accumulation of histone H3 methylated on lysine 9, phosphorylation of p53 at serine 15 and enhanced expression of the senescence-associated chemokine CXCL10 mRNA, were detectable in the tumours of the animals treated with MKL1 and 2 siRNA.