In human melanoma cells, PI3K negatively regulates STAT activity.193 In mammary epithelial cells, the JAK2/STAT5 pathway controls mammary epithelial cell survival and death through direct interaction with the p58α regulatory subunit of PI3K and upregulation of the expression of p85α (Pik3r1), p110α (Pik3ca), and AKT1.194 In cytokine-receptor-like factor 2-rearranged B-precursor acute lymphoblastic leukemia, increased pJAK2, pSTAT5, and pS6 levels were observed in patient samples. Here, PIK3CA is linked to acute lymphoblastic leukemia.