The expression of uc.38, a T-UCR, was down-regulated in both breast cancer tissues and breast cancer cell lines. uc.38 was expressed at significantly lower levels in larger tumours and tumours of more advanced stages.up-regulation of uc.38 expression inhibited cell proliferation and induced cell apoptosis.uc.38 suppressed breast cancer. uc.38 negatively regulated the expression of the pre-B-cell leukaemia homeobox 1 (PBX1) protein and subsequently affected the expression of Bcl-2 family members,ultimately inducing breast cancer cell apoptosis.The level of expression and type of TUCR have been shown to be closely related to the survival rates of patients with cancer.