IGFBP3 and lung cancer: Using the CD44‐negative normal human lung cells (HFL1) and human lung cancer cells (A549) known to express CD44 [66, 75], we found that the IGFBP‐3 l‐peptide, but not its mutant, reduces A549 cell viability by disrupting HA‐CD44 interactions (Fig. 2B,C), a result consistent with our previous reports [48].