CD44 and neoplasm: A blocking antibody or siRNA knockdown of Notch-4 has been shown to reduce the stem cell population, inhibiting tumor formation from EpCAM+CD24-CD44+ CSCs and that this effect was greater than Notch-1 inhibition [71],[73], this suggests that Notch4-targeted therapies may be more effective than Notch1-targeted therapies in targeting breast CSCs.