Furthermore, Dworakowska et al (Dworakowska et al. 2009) found that NSCLC patients with very high AI values combined with very high PCNA (proliferating cell nuclear antigen) labeling index had a particularly poor prognosis and concluded that joint analysis of several apoptosis, proliferation and cell cycle regulation biomarkers may provide more useful prognostic information as compared to AI alone. This evidence concerns the gene PCNA and non-small cell lung carcinoma.