S100A4 and breast carcinoma: Chen et al (2001) using an optical biosensor, demonstrated interaction of S100A4 with nonmuscle myosin and p53 in calcium-independent manner suggesting appearance of novel binding sites. Moreover, immunofluorescence studies revealed a novel, calcium-independent localisation of S100A4 to the leading edge of motile breast carcinoma cells (Kim and Helfman, 2003).