MAP2K1 and cancer: One of these was PEBP4, a suppressor of proliferation and invasion in ovarian tumour cell lines,32 and a RAF1- and MEK1-binding protein that inhibits tumour necrosis factor-α-induced apoptosis.33 PEBP4 was significantly elevated in sera from cancer cases prior to diagnosis and featured in one of the top multivariable longitudinal models.