NOTCH4 and osteosarcoma: Zhang et al (2008) carried out RT–PCR for two osteosarcoma patient specimens and found that both expressed Notch1, Notch2, Notch4, HES1, and HERP2 mRNA, although they did not present RT–PCR data. We also carried out RT–PCR using osteosarcoma biopsy specimens and detected the PCR amplicon of Notch1 in all specimens after 25-cycle reaction, although RT–PCR revealed that expression of Notch1 was decreased in osteosarcoma human specimens compared with normal bone.