In the second metastatic melanoma cell line tested (i.e. M2), although the stable knockdown of PKD1 by specific shRNAs induced the expression of E-cadherin, these shPKD1-induced E-cadherin molecules could only be detected as cleaved form in the colony spheres of cells cultured in semi-solid medium or as secreted molecules in the conditioned medium of the adherent cells. The gene discussed is PKD1; the disease is metastatic melanoma.