RELA and breast cancer: However, ING4 overexpressing cells contained measurably less p-p65/RelA (Ser536) in both cytosolic and nuclear fractions (2- to 5-fold), indicating that phosphorylation of p65/RelA at the amino acid residue serine 536 was inhibited by ING4 overexpression in T47D and MCF7 breast cancer cells (Figure 3A–B).