ID1 and breast cancer: On the other hand, treatment with BMP-2 in the breast cancer cell line C2C12 resulted in increased expression of Id-1 (Katagiri et al, 1994; Nobta et al, 2005; Raida et al, 2005; Langenfeld et al, 2006), while BMP-2 also positively regulated the expression of Id-1 in certain cell contexts (Locklin et al, 2001; Takeda et al, 2004).