onable to assume that RIC8 might also be involved in ciliary beat regulation in the oviduct since it amplifies the signals from G-protein coupled receptors and co-localizes in cilia with Gi2. In conclusion, we present novel data about a dynamic localization of guanine nucleotide exchange factor RIC8 in mouse oogenesis, at fertilization and initial steps of oocyte first cleavage. We demonstrated for the first time that the redistribution of RIC8 during mouse oogenesis is highly regulated and strictly follows the oocyte growth and maturation, as well as the phases of meiosis. The results of present study form a good basis for the further unraveling of the RIC8 function in gametogenesis, fertilization and early development of mammals. Acknowledgments We thank Mall Kure, Mario Plaas and personnel of IMCB animal facility for excellent technical assistance. In memory of Merly Saare, one of the leading authors of this study, who passed away during the finalization of this manuscript. ~~ ~~ Patient-derived tumor xenografts mouse models PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19709857 has been largely used for the study of cancer biology, pre-clinical test of new drugs or new drug combinations, and more recently as avatars to pursue personalized therapeutic regimens. Xenografts are usually obtained by subcutaneous implantation of small pieces of tumors into the flank of mice. In case of leukemia, xenografts are obtained by injection of 10 million cells into the tail vein or intrafemorally. Subcutaneous tumor growth and drug response is easily monitored by measuring tumor volume with an external caliper, though with lower accuracy than more sophisticated imaging methods. Monitoring LGX-818 leukemia xenografts is usually done by flow cytometry analysis of 1 / 13 Plasma Hsp90 for In Vivo Monitoring of ALL Competing Interests: The authors have declared that no competing interests exist. human CD45+ cells in peripheral blood. However, leukemia homing and progression in nonobese diabetic /SCID mouse occurs primarily in the bone marrow, liver and spleen. Migration of leukemia cells into circulation is an active process controlled by SDF1/ CXCR4 axis. Consequently, the number of leukemia cells in peripheral blood may not always represent total leukemia burden, especially at earlier stages of leukemia engraftment and progression. Alternatively, high sensitivity methods for in vivo leukemia monitoring by bioluminescent or fluorescent imaging analysis require genetic modification of leukemia cells, which is not a straightforward method when handling with primary leukemia cells. Soluble proteins secreted or released by leukemia cells into the circulation could be useful markers for earlier engraftment PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19710694 detection and to monitoring the dynamic growth of leukemia in mice. Serum levels of prostate-specific antigen have been shown to correlate with tumor volume in animal models of prostate cancer. Similarly, human specific lactate dehydrogenase isoenzymes and the nuclear matrix protein 41/7 were found to be useful serologic markers to monitor the dynamic growth of human leukemia in mice, though with low sensitivity in early stages of tumor growth. Detection of human pre-B acute lymphoblastic leukemia cell line Nalm-6 was only possible when the number of Nalm-6 cells in bone marrow was equal or higher than 7.2% 
and 13.7%, respectively, of total cell numbers. In this manuscript, we report on a highly sensitive method for detecting and monitoring ALL in mice by measuring plasma levels of human Hsp90. Materials and Methods
