Figure 2

Representative results of immunohistochemistry of Id-1 to Id-4 expression in oesophageal specimens. (Panel 1) Id-1 expression was negative to weak in non-neoplastic oesophageal epithelium (A), but increased in ESCC specimens (B–E). While a low level of nuclear Id-1 staining was detected in primary ESCC at M0 stage (B), a significantly higher level of nuclear Id-1 staining was observed in tumours at M1 stage (C). ESCC at T2 stage (D) had weak cytoplasmic Id-1 staining while a high-level cytoplasmic Id-1 expression was detected in T4 stage tumour (E). (Panel 2) Id-2 staining was relatively weak in normal oesophageal epithelium (F) while was higher in tumour specimens (G and H). High level of cytoplasmic Id-2 staining was observed in well-differentiated tumours (G) but was significantly lower in poorly differentiated tumours (H). (Panel 3) Id-3 staining was high in both normal oesophageal epithelium (I) and ESCC specimens (J), with mainly nuclear staining in the former one and both cytoplasmic and nuclear staining in the later one. (Panel 4) Id-4 expression was relatively weak in normal oesophageal epithelium (K) and higher in tumour specimens (L). Image was captured at × 400 magnification.