To determine the precise role of intracellular LIF in NPC invasiveness, we utilized TALEN technology to generate stable clones with mutations in the signal peptide region (cLIF clones) to induce cytoplasmic accumulation of LIF or with loss of the initiating codon in one allele (LIF+/− clone) to reduce LIF expression (Fig. 2a; Supplementary Figure 2). The gene discussed is LIF; the disease is nasopharyngeal carcinoma.