Abstract: Objective To investigate hCLP46 expression and significance in two breast cancer cell lines with different invasive and metastatic potentials.Methods hCLP46 expression at mRNA level was detected by RT-PCR in two different breast cancer cell lines(MCF-7 which was low metastatic and MDA-MB-231 which was medium metastatic).MCF-7 and MDA-MB-231 cell lines were cultured with 100μmol/L TGF-β for 72 hours respectively as the experimental group.MCF-7 and MDA-MB-231 cell lines were cultured without TGF-β for 72 hours as the control group.Western-blotting method was used to test the P15 expression in the two cell lines.Results RT-PCR results showed that the reference gene GAPDH expressed similarly in the two cell lines,and hCLP46 expression showed higher in MDA-MB-231 cell line than that in MCF-7 cell line.The expression of P15 in both two cell lines decreased after adding TGF-β,compared with the corresponding control cell lines.The expression of P15 in MDA-MB-231 cell line was lower than that in MCF-7 cell line.Conclusion It was shown that over expression of hCLP46 may inhibit the expression of P15 inducted by TGF-β in MDA-MB-231 and MCF-7 cell line,hCLP46 maybe play a role in the development of breast cancer.