BCL2L1 and pachyonychia congenita: Indeed, some PC cell lines exposed to 5-FU or gemcitabine show enhanced MCL-1 and/or BCL-xL expression and a higher ratio of these proteins to some proapoptotic proteins, such as BAX and BAK, suggesting that these proteins, especially Mcl-1, might be key players in the chemoresistance of PC [100].