PTPN11 and acute lymphoblastic leukemia: In contrast, mutations in PTPN11, NRAS, KRAS, and NF1 genes were detectable in none, three, four, and one of 16 t(1;19)‐ALL cell lines, respectively, and gene mutation in RAS pathway was detectable in seven out of 16 t(1;19)‐ALL cell lines.