<prompt> Substance playing a role in tumor metastasis cascade isCollagenase IVTNF-alphaCD99NM23  <response>: Ans is a i.e. Collagenase IVVarious steps of metastasis and molecules involvedDetachment of tumor cells - Down regulation of expression of either E-cadherins or cateninsAttachement to ECM including basement membrane - Tumor cells express integrins that helps in the attachement.Degradation of ECM - proteolytic enzymes most impoant proteases are metalloproteinases MMPs including collegenase IV.Vascular dissemination and homing of tumor cells - Among adhesion molecule CD44 is of paicular interest. 