The similar result was also observed in cancer cells: In the E-cadherin positive primary breast cancer cell line MCF-7 rather than the E-cadherin negative invasive breast cancer cell line MDA-MB-231, overexpression of insulin-like growth factor I receptor induced ZO-1 expression and increased cell aggregation, and the following ZO-1 inhibition prevented the course, demonstrating that ZO-1 is crucial for cell aggregation which is dependent on E-cadherin-mediated adherens junction formation 45. Here, TJP1 is linked to breast cancer.