MDA-MB-435S is a spindle shaped strain which evolved from the parent line (435) isolated in 1976 (R. Cailleau et al.) from the pleural effusion of a 31 year old female with metastatic ductal adenocarcinoma of the breast. Parental cells displayed the dispersed pattern (type II) when treated with immunofluorescent stain for tubulin. Recent findings point to a rather melanocytic origin of this cell line (Ellison 2002).