Effect of HPV-16 E5 expression on tyrosinase activity and pigment deposition and anchorage independent growth of amelanotic melanomas. Colony formation under anchorage independent culture conditions. The E5 expressing FRM cells displayed a moderated colony formation activity and a variable degree of pigment deposition while no colony nor pigmentation could ever been shown among control parental cells. Similar results were shown with M14 cells (data not shown). A representative experiment in a set of 3.