regulation such as posttranslational modifications to reduce its inhibitory activity.” Or it may be due to a reduction of the TID domain to bind and inhibit telomerase as a result of proteins interacting with PINX1, such as PIN2/TRF1 which colocalizes PINX1 in cells. There are two types of PINX1: nuclear PINX1 which is associates with telomeres and CAC repeats and nucleolar PINX1 does not bind directly to the telomeres, but instead interacts with TRF1. Nucleolar hPINX1 mediates the movement of hTERT and TRF1 to the nucleolus. Over-expression of nucleolar hPINX1 leads to increased TRF1 in the nucleolus and binding to telomeres. However, this accumulation in the nucleolus was not found in ALT (alternative lengthening of telomeres) cells indicating that PINX1 function is telomerase dependent. hPINX1 is found more in the nucleoplasm during the S phase which is also when telomerase is released into the nucleoplasm indicating that hPINX1 may inhibit telomerase during the S phase. Cancer PINX1 is located at 8p23. Heterozygosity of this area is frequently lost in tumors including liver, prostate, prostate, colorectal, lung, and head and neck. Most PINX1 mutant tumors are carcinomas. PINX1 expression is significantly reduced in these tumors. This significance was shown with HT1080 cells, which increased tumorigenicity with decreased PINX1 expression. Over-expression of PINX1 in HT1080 cells did not allow them to form tumors in mice. Therefore, PINX1 may be a tumor suppressor. PINX1 expression is a predictor of cervical squamous cell carcinoma (CSCC) cells response to cisplatin/paclitaxel chemotherapy. High levels of PINX1 correlated to response. But the levels of PINX1 were only associated with cytotoxicity of paclitaxel. Reduced levels of PINX1 led to increased paclitaxel cytotoxicity. “The ability of PINX1 to stabilize the tension between sister kinetochores and maintain the spindle assembly checkpoint was the main reason CSCC cells undergo apoptosis when treated with paclitaxel.” Chemoradiotherapy is a standard treatment for advanced esophageal squamous cell carcinoma (ESCC). Reduced PINX1 expression did not affect ESCC cells response to 5-fluorouracil and cisplatin, but did increase efficacy of radiation therapy. High levels of PINX1 led to reduced cell death due to radiation. “PINX1 resistance to radiotherapy (RT) was attributed to PINX1 maintaining telomere stability, reducing ESCC cell death by RT-induced mitosis catastrophe.” High levels of PINX1 is a predictor of short disease-specific survival. PINX1 levels were found to be reduced in urothelial carcinoma of the bladder (UCB) compared to normal urothelial bladder epithelium. “PINX1 levels