The 20 leukemic patients will be classified into three age groups according to the ages that will be available at the time of sample collection.~All patients will be recruited from Tanta Oncology Center, Tanta University.~The study will be approved by the Research Ethics Committee of Tanta University and college of Pharmacy ethical committee.~An informed consent will be obtained from parents of all patients in this research before enrollment.~All patients' data will be private and confidential. Any unexpected risks that may appear during the course of the research will be reported to patients and the ethical committee on time.~Blood Samples will be obtained from healthy pediatric subjects of the same ages of the diseased group subjects (Samples will be obtained from subjects from a primary care center during their routine blood analysis excluding patients of chronic diseases, patients receiving any medications, and patients of impaired kidney or liver functions).~P-glycoprotein expression will be estimated in all samples using Permeability glycoprotein (P-gp), ELISA Kit, and its expression will be traced with development from the youngest till the oldest age available, this will also be compared with normal healthy pediatric subjects.
Determine P-glycoprotein expression in blood samples of Acute Lymphocytic leukemia (ALL) pediatric patients receiving MTX treatment and trace its ontogeny and compare it with its expression in pediatric healthy subjects. In addition, to determine the correlation of P-glycoprotein expression and Methotrexate concentration at steady state.