Dr. Liu’s research is primarily focused on the identification and characterization of function and signaling mechanism of novel receptors and enzymes for the discovery and development of therapeutics in the area of cancer and immunology.  In the biotech/pharmaceutical industry, he led multiple projects in delineating the function and mechanism of many orphan receptors, developing HTS assays, identifying and optimizing drug leads, and delivering clinical candidates.  In particular, Dr. Liu championed the drug discovery project of tryptophan hydroxylase 1 (TPH1) at Lexicon Pharmaceuticals that led to the discovery and development of a first-in-class, orally active inhibitor of TPH1 (Xermelo®) that was approved by FDA for patients from carcinoid syndrome diarrhea.  Since joining IMM at UTHealth,  Dr. Liu has been focused on delineating the functions and mechanisms of LGR4-6 (leucine-rich repeat-containing, G protein-coupled receptor 4, 5, & 6) group of receptors in stem cell survival and cancer development.

Research Projects

  • Function and mechanism of LGR4-6 in modulation of Wnt signaling for survival and differentiation of adult stem cells in the gastrointestinal tract.
  • Roles and mechanisms of R-spondin/LGR4-6 in cancer initiation and progression.
  • Discovery and development of novel therapeutics targeting LGR4-6 and their ligands for cancer treatment.


  1. Park, S., Cui, J., Yu, W., Wu, L., Carmon, K. S., and Liu, Q. J. (2018) Differential activities and mechanisms of the four R-spondins in potentiating Wnt/beta-catenin signaling, J Biol Chem 293, 9759-9769. PMC6016459
  2. Carmon, K. S., Gong, X., Yi, J., Wu, L., Thomas, A., Moore, C. M., Masuho, I., Timson, D. J., Martemyanov, K. A., and Liu, Q. J. (2017) LGR5 receptor promotes cell-cell adhesion in stem cells and colon cancer cells via the IQGAP1-Rac1 pathway, J Biol Chem 292, 14989-15001. PMC5592675
  3. Gong, X., Yi, J., Carmon, K. S., Crumbley, C. A., Xiong, W., Thomas, A., Fan, X., Guo, S., An, Z., Chang, J. T., and Liu, Q. J. (2015) Aberrant RSPO3-LGR4 signaling in Keap1-deficient lung adenocarcinomas promotes tumor aggressiveness, Oncogene 34, 4692-4701. PMC4476959
  4. Carmon, K. S., Gong, X., Yi, J., Thomas, A., and Liu, Q. (2014) RSPO-LGR4 functions via IQGAP1 to potentiate Wnt signaling, Proc Natl Acad Sci U S A 111, E1221-1229. PMC3977305
  5. Gong, X., Carmon, K. S., Lin, Q., Thomas, A., Yi, J., and Liu, Q. (2012) LGR6 Is a High Affinity Receptor of R-Spondins and Potentially Functions as a Tumor Suppressor, PLoS One 7, e37137. PMC3355120
  6. Carmon, K. S., Lin, Q., Gong, X., Thomas, A., and Liu, Q. (2012) LGR5 Interacts and Cointernalizes with Wnt Receptors To Modulate Wnt/beta-catenin Signaling, Mol Cell Biol 32, 2054-2064. PMC3372227
  7. Carmon, K. S., Gong, X., Lin, Q., Thomas, A., and Liu, Q. (2011) R-spondins function as ligands of the orphan receptors LGR4 and LGR5 to regulate Wnt/beta-catenin signaling, Proc Natl Acad Sci U S A 108, 11452-11457. PMC3136304