However, this number might not be directly correlated with the number of metastases as the L1CAM knockdown probably affects steps of the metastatic cascade following extravasation as the increase in p38 phosphorylation (S3 Fig) indicates that the melanoma cells in the L1 kd metastases are more stressed than the Luc controls, but L1CAM expression (albeit lower than in the luc controls) could be detected even in the metastases formed by the L1CAM knockdown cells (Fig 3) indicating that L1CAM is necessary for the outgrowth of metastases. The gene discussed is L1CAM; the disease is melanoma.