Morrison is the director of Children's Medical Center Research Institute at UT Southwestern (CRI),[1] a nonprofit research institute established in 2011 as a joint venture between Children’s Health System of Texas and UT Southwestern Medical Center.

[11] He earned a Ph.D. in immunology in 1996 for working on the isolation and characterization of blood-forming (hematopoietic) stem cells in the laboratory of Dr. Irving L. Weissman at Stanford University.

[12] Morrison then worked as a postdoctoral fellow on the isolation and characterization of neural crest stem cells in Dr. David Anderson’s laboratory at the California Institute of Technology from 1996 to 1999.

The Morrison laboratory identified a series of key stem cell self-renewal regulators, revealing several important principles.

[24] They showed in that study that most HSCs reside adjacent to sinusoidal blood vessels in the bone marrow and spleen.

[27] The identification of these niche cells made it possible to test whether hematopoiesis or osteogenesis are regulated by yet undiscovered growth factors in the bone marrow.

As a result of this work, the Morrison lab discovered Osteolectin/Clec11a, a bone-forming growth factor made by Leptin Receptor+ cells that is required to maintain the adult skeleton by promoting osteogenesis.

[30] The rare melanoma cells that survive during metastasis undergo reversible metabolic changes that confer oxidative stress resistance.