MDA-MB-435: the questionable use of a melanoma cell line as a model for human breast cancer is ongoing.

In September 2006, Rae et al. provided unmistakable evidence that the MDA-MB-435 human breast cancer cell line is identical to the M14 human melanoma cell line. This discovery was no surprise to the breast cancer research community. In fact, the expression of melanocyte-specific marker proteins by MDA-MB-435 cells was first recognized many years ago. In 2007, the year after MDA-MB-435 cells were officially redefined as melanoma cells, this mix-up has gained a new aspect: We could easily identify 20 novel studies published in the recent issues of leading journals which simply proceeded to employ MDA-MB-435 cells as a model system for human breast cancer. Here we want to draw attention to this questionable practice which should further raise our (self-) skepticism and awareness about the true origin, the identity and molecular properties of any biological materials used in cancer research.