Lately, I have been having more of a difficult time lifting my stem cells during passages. I am currently using rhlaminin-521 to coat my plates and versene to lift the cells. Previously, I was not having an issue when using vitronectin for coating. I incubate my cells for 5-10 minutes in versene to allow for lifting, but a lot of them still stay adhered to the plate. Has anyone had this issue? Or does anyone have suggestions?