However, other work has shown that PKM2 is dispensable for the growth and maintenance of xenograft tumors [9], that loss of PKM2 can promote progression of BRCA1 loss-driven breast cancer [10] and medulloblastoma tumor growth [11], and that PKM2 is not required for leukemia or liver tumor formation [12, 13]. This evidence concerns the gene PKM and breast carcinoma.