TP53 and acute lymphoblastic leukemia: In an in vitro leukemic niche (LN) model [26], we have recently shown that B-ALL cell lines induced in MSC a significant increase in senescence-associated β-galactosidase (SA-βGAL) activity together with an augmented p53 gene expression and cytoplasmic reactive oxygen species (ROS) production, and a subsequent cell cycle arrest [27].