PIK3R1 and acute lymphoblastic leukemia: Interestingly, the analysis of Hispanic B-ALL patients from the TARGET database corroborated the downregulation of IL7R, which is considered a common driver mutation of ALL [33, 39], but not that of PIK3CG. Our results showed that these B-ALL patients expressed low levels of PIK3CA, PIK3CB, and PIK3CD, which are Class I PI3Ks, such as PIK3CG, PIK3R1, and PIK3R2. Likewise, Ma et al. observed PIK3CA and PIK3R1 as the most frequent mutations in the PI3K and RAS pathways in leukemias.