Robert L. Kortum, M.D., Ph.D.

Robert L. Kortum, M.D., Ph.D.

Robert Kortum

Name: Robert L. Kortum, M.D., Ph.D.

Department of Primary Appointment: Pharmacology
Position: USU Faculty
Title: Assistant Professor

Affiliated Departments: Molecular & Cell Biology,

Research Interests:
Signal Transduction, Cancer

Email: (link sends e-mail)
Office Phone: (301) 295-3249
Fax Number: (301) 295-3220
Room: C2027

Department Website


  • B.S., Chemistry and Mathematics, University of Nebraska-Lincoln
  • Ph.D., Pathology and Microbiology, University of Nebraska Medical Center
  • M.D., University of Nebraska Medical Center
  • Postdoctoral Training, National Institutes of Health

Oncogenic RTK/Ras signalingTargeting RTK/Ras signaling in cancer


Oncogenic mutations in RTK/Ras signaling pathways account for 30-50% of tumors. For cancers driven by mutated or hyperactivated RTKs, targeted therapeutics have shown enormous potential, however, resistant cells often emerge that continue to rely on RTK signaling to drive their oncogenic phenotype. Similarly, for cancers driven by the Ras effector B-Raf, resistance to kinase inhibit ors often involves hyperactivation of RTK signaling.  It is therefore incumbent to find alternative therapeutic targets within the RTK/Ras pathway that when inactivated will limit oncogenesis.



Simultaneous targeting of multiple signaling proteins within the same pathway has the potential to overwhelm a cancer cell’s ability to mutate and become resistant to therapy. A major goal of our laboratory is to elucidate those signaling proteins downstream of RTKs that can be targeted either alone or in combination with current therapeutics to treat cancer.


Schematic depicting oligomerization of RTKs by Grb2—Sos—Grb2 complexesExamining novel Sos-dependent functions in RTK/Ras signaling


The RasGEFs (Guanine Exchange Factors) Sos1 and Sos2 (Son of Sevenless 1 and 2) are central to signal transduction from receptor tyrosine kinases (RTKs) to the small G protein Ras, and recruitment of the RasGEF Sos1 by the adaptor Grb2 to receptor signaling complexes is an essential early step in normal Ras activation. In T cells, Sos1 and Grb2 show multipoint binding that nucleate higher-order protein complexes at the cell surface necessary to drive cell fate decisions (Kortum, Sci. Signaling, 2013).  We are currently examining whether similar mechanisms are important to both normal and oncogenic RTK/Ras signaling