Further studies showed that PTC-209 downregulated the level of Bmi-1 protein without affecting the levels of Bmi-1 transcript in MM cells (Wang et al., 2017) and biliary tract cancer (BTC) cells (Mayr et al., 2016), suggesting that it might also regulate Bmi-1 expression at the posttranscriptional level. This evidence concerns the gene BMI1 and biliary tract cancer.