The HK-1 and C666-1 cells also responded to co-inhibition of MCL-1 and BCL-2 but synergism was mostly attained at higher concentrations of the drugs (> 1 μM) demonstrating that inhibition of MCL-1 and BCL-XL are better therapeutic targets for killing NPC cells. This evidence concerns the gene MCL1 and nasopharyngeal carcinoma.