Cancer has been a major health issue worldwide. The major challenge by cancer is the metastasis of malignant tumor cells, which allow malignant tumor cells to spread to different tissues of the body. Mechanical properties of cancer cells play an important role in highly dynamic metastasis of cancer cells, which has drawn the attention of many scientists including biophysicists. Myosin 10 was recently reported to be involved with the aggressive metastasis of cancer cells. Myosin 10 mediates the formation of filopodia - a finger-like cell membrane protrusion which is involved in many cellular processes including extracellular sensing and signalling, cell-cell interaction and cell migration. In this thesis, I explored the roles of Myosin 10 on the physical properties of MDA-MB-231 (a malignant breast cancer cell line). Magnetic tweezers with an electromagnet are used to measure the creep response of cells. Measurements were done on the cells growing on two different substrates: PDL and collagen-I, where a substrate formed by collagen-I is closer to the real extracellular matrix for cancer cells. My results show that Myosin 10 increases the fluidity of cells on both substrates, implying that cells with high Myosin 10 expression may be more fluid-like and are capable to move aggressively. Moreover, this tendency becomes more significant when cells are seeded on collagen-I (a more realistic substrate). Furthermore, the impact of Myosin 10 on collective cell migration was studied. Two-dimensional in-vitro wound healing assay on breast cancer cells reveals that cells with higher Myosin 10 expression level have a higher migration rate. My results agree with early research showing filopodia-mediated migration of cancer cells as cell clusters. My results shows that Myosin 10 plays an important role in shaping mechanical properties of cancer cell.