As shown by in vitro studied herein, the expression of IL-9R was detected at both the mRNA and protein levels within the five lymphoma cell-lines, including the DLBCL cell-lines LY1 and LY8, mantle cell lymphoma (MCL) cell-lines Mino and SP53, as well as the human acute T cell leukemia cell-line Jurkat. This evidence concerns the gene IL9R and mantle cell lymphoma.