HEXIM1 and breast carcinoma: HEXIM1 also interacts with p53 in MCF7 breast cancer cells, and overexpression of HEXIM1 enhances the interaction and inhibits p53 ubiquitination, resulting in enhanced p53 stability and activation of p53 target gene expression required for DNA repair, apoptosis, and differentiation (Lew et al, 2012, 2013).