CDH1 and neoplasm: However, E-cadherin was significantly downregulated in erlotinib-treated tumors (P = 0.001, Student’s t test; Figure 5A and B), which is consistent with the so-called ‘E-cadherin paradox’ described in clinical IBC in which E-cadherin expression is maintained in IBC tumors and metastases but its downregulation leads to tumor regression [21].