TJP1 and melanoma: ERK-activity has also been found to be localized more in the growing periphery of spheroids, which is also found in patient melanoma lesions, and spheroid melanoma models have been applied to study invasion capacity, BRAF targeting, zonula occludens protein 1 (ZO-1) contribution to melanoma oncogenesis, MAPK pathway responses to MEK inhibitors, among others (Beaumont et al., 2014).