Wu-Ming Qin, Kun Wang, Jia-Rong Huang, Xiao-Long Mei and Zhi Shi 2021. Sildenafil Induces Cell Cycle Arrest and Apoptosis in Human Colorectal Cancer HT-29 Cells. Journal of Cancer Research Updates. 7, 2 (Aug. 2021), 59–63. DOI:https://doi.org/10.6000/1929-2279.2018.07.02.4.