Provided herein are methods of producing natural killer (NK) cells using a three-stage expansion and differentiation method with media comprising stem cell mobilizing factors. Also provided herein are methods of suppressing tumor cell proliferation using the NK cells and the NK cell populations produced by the three-stage methods described herein, as well as methods of treating individuals having cancer or a viral infection, comprising administering the NK ce3lls and the NK cell populations produced by the three-stage methods described herein to an individual having the cancer or viral infection.
