Incubation of GS-168AT2 with the hLT cell line NCI-H460 leads to the association of GS-168AT2 with both CD9 and CD81, and treatment of NCI-H460-xenografted Nude mice with GS-168AT2 leads to a drastic inhibition of tumour growth, which is associated with the in vivo downregulation of CD9 in tumours. This evidence concerns the gene CD9 and neoplasm.