The cancer diagnosis relies on morphological examination of human cells or tissue samples: This is considered the 'gold standard' for the diagnosis of malignancy in any organ system. However, diagnosis based on morphological examination can be difficult, recent studies recognized the cell elasticity changes as a marker for cancer detection. A metrological characterized AFM can be used to make reproducible elasticity measurements on biological samples. In this paper a method to accurately measure a cell elasticity change based on measurement of a stable and homogeneous material is proposed. Nanoindenter characteristics (nanoindenter with pyramidal tip and triangular shape) and indentation parameters (0.1 V as approaching point, 5 um/s as indentation speed and indentation load of 0.4 V) were found feasible for all tested samples. A modal cell elastic modulus of 0.5 kPa for lung tumor cell and a limit AFM measurement reproducibility of 4% was obtained.