CCL21 and acute lymphoblastic leukemia: A well-described GPCR in ALL is C–C chemokine receptor type 7 (CCR7), and it hademerged as a significant factor in the pathogenesis and specifically the progression ofT-cell ALL (T-ALL).49 CCR7 has been implied to play a vital role in thedirected migration and lymph node homeostasis through its interaction between thechemokines CCL19 and CCL21.50 In T-ALL and lymphocytic leukemia, CCR7is frequently overexpressed, facilitating the trafficking of leukemic cells to lymphoidorgans, where chemokines are abundant.