GREM1 and breast carcinoma: However, the 21NT mammary carcinoma cell line fails to degrade both endogenous and transgenic hMps1, and GFP-hMps1T468A can accelerate centrosome re-duplication in 21NT cells, suggesting that defects in hMps1 degradation can also be caused by deficiencies in the factors that regulate its degradation [47].