<prompt> Which of the following is not expressed in majority of cases of pediatric B-cell acute lymphoblastic leukemia?Terminal deoxynucleotidyl transferase TdTCD19CD10CD7  <response>: CD19 is a pan B-cell marker. CALLA common acute lymphoblastic leukemia antigen is CD 10. CD45 is known as leukocyte common antigen LCA. Terminal deoxynucleotidyl transferase TdT, a specialized DNA polymerase that is expressed only in pre-B and pre-T lymphoblasts, is positive in more than 95 of cases. CD7 is commonly expressed in T-cell ALL. 