BCCIP was originally identified as a BRCA2 and CDKN1A interacting protein that has been implicated in maintenance of genomic stability, cell cycle regulation, and microtubule dynamics. The secondary genetic alternations may overcome the progression suppression imposed by BCCIP deficiency through a synthetic viability mechanism. Knockdown of YY1 inhibited the binding of BCCIP itself at BCCIP promoter region proximal to TSS, demonstrating that transcriptional regulation of the YY1 on BCCIP can be modulated by BCCIP itself in a YY1-dependent fashion. BCCIP (BRCA2 and CDKN1A interacting protein) plays a critical role in maintaining the critical functions of p53 in tumor suppression and response to therapy. Celecoxib affects the functions of p53 and inhibits the recovery from the irradiation-induced injury by up-regulating the expression of BCCIP, and subsequently regulates the expressions of genes such as p21 and Cyclin B1 to enhance the radiosensitivity of HCT116 cells in a COX-2 independent manner.