By applying AFMOTs to trap and deform individual cells, we differentiated the nontumorigenic breast epithelial cell line (MCF10A) from its cancerous PTEN mutants (MCF10 PTEN-/-) based on the measured cellular deformability, while the cell deformability can be used as a biomarker of cancer and many other types of diseases21. The gene discussed is PTEN; the disease is cancer.