However, the expression levels of ABCC1 and ABCC2 drug efflux transporters were very similar between the non-tumor-initiating subpopulation (CD44−CD133- and CD44−CD133+ Caco-2 cells) and the tumor-initiating subpopulation (CD44+CD133+ Caco-2 cells). Here, ABCC2 is linked to neoplasm.