Insulin Like Growth Factor Binding Protein Like Protein 1 (IGFBPL1)

Cai et al. (2005) cloned IGFBPL1 cDNA from human testes. The deduced 278-amino acid protein contains a signal peptide and conserved motifs typical of the IGFBP family. It shares 52% sequence identity with IGFBP7. Expression of the cDNA in COS-7 cells yielded a product of 38 kD. Semiquantitative real-time PCR revealed highest levels of expression in brain and testis, and lower levels in prostate, bladder, and lung. Expression was downregulated in all 5 colon tumor samples and 4 of 6 lung tumor samples tested.

Using transient transfection experiments, Cai et al. (2005) demonstrated that IGFBPL1 significantly inhibited the growth of HeLa cells. They suggested that an apoptotic mechanism was responsible for the growth inhibition.