Sung-Han Hsiao, Shi-Yu Luo, Ching-Ya Su, Wei-Cherng Tuo, Cheng-Ting Chiang, Yan-Qing Li, Yang-Hui Huang and Chung-Pu Wu (2014) “The Overexpression of ABCG2 Reduces the Efficacy of Volasertib (BI 6727) and GSK641364 in Human S1-M1-80 Colon Carcinoma Cells”, Journal of Cancer Research Updates, 3(2), pp.  108–116. doi: 10.6000/1929-2279.2014.03.02.5.