NUMB and esophageal squamous cell carcinoma: On the other hand, NUMB up-regulation has been associated with poor prognosis in certain tumors, such as hepatocellular carcinoma (HCC) [193] and esophageal squamous cell carcinoma (ESCC), where NUMB overexpression has been linked to increased tumor recurrence and poor overall survival [194], but more specifically, the possible functional diversity of the isoforms has been investigated.