Increased cell death was detected in the case of KCs cultured with heat-pretreated CM from Tsc1+/+ hepatocytes, which suggested that hepatocytes produce certain proteins that maintain KC survival (Fig. 2j); however, cell death was similar in KCs cultured with heat-pretreated CM from Tsc1+/+ hepatocytes and Tsc1-/- hepatocytes. Here, TSC1 is linked to dry eye syndrome.