ICAM1 and cancer: CD9 is also shown to associate directly with ADAM17 on the surface of different cell types (cis interactions), including leukocytes and cancer cells, and through this association exerts an inhibitory effect on ADAM17 sheddase activity against its substrates, including TNFα, ICAM-1 [83,143,144,145,146] or ALCAM [55,82,83].