This communication reports that three prostate cancer cells of differing metastatic potential were discriminated based on their Young's moduli (LNCaP - 287 +/- 52 N m(-2), PC-3 - 1401 +/- 162 N m(-2) and BPH - 2797 +/- 491 N m(-2)) which were determined using AFM and the Hertz model.