IGFBP3 and lung cancer: In summary, due to the high variability of the IGFBP action in the IGF network, it is possible to subgroup IGFBP genes into two categories: (i) oncogenes, whose products are upregulated in lung cancer, i.e., IGFBP-2/-4/-5; and (ii) tumor suppressors, that are downregulated in lung cancer, i.e., IGFBP-3/-6.