KMT2A and breast cancer: However, MLL3 (2/20, p = 0.49) and EP300 (3/20, p = 0.23) exclusively mutated in primary tumors indicating that chromatin remodeling genes (MLL, MLL3, EP300 and EP400) may play distinct roles in primary and recurrent BC tumorigenesis (Figure 2A and Supplementary Table 5).