MKI67 and breast neoplasm: Moreover, the analysis of LDHB mRNA levels in 21 human breast tumor tissues showed that samples with Ki-67 labeling index ≥ 20% had higher levels of the LDHB transcript than those with a Ki-67 < 20%, reinforcing that the overexpression of the LDHB enzyme is necessary for a faster tumor growth [30, 31] and a more aggressive tumoral behavior [57, 58].