Abstract: Objective To investigate the relationship of the expressions of protein cPLA₂ and ERK2 in the occurrence, development and prognosis of breast carcinoma.Methods The expressions of protein cPLA₂ and ERK2 in 48 breast cancer cases, 21 breast adenosis tissue cases and 21 breast fibroadenoma cases by SP immunohistochemical method.Results The expression of cPLA₂ in breast cancer tissue is apparently higher than that in breast adenosis tissue and breast fibroadenoma, and the differences are remarkably significant(P＜0.05).After statistical analysis, it is found that the cPLA₂ expression has positive relationship with TNM stage(P＜0.05);The expression of cPLA₂ protein levels increased remarkably in lymph node metastasis groups in comparison to no lymph node metastasis groups, and the differences are remarkably significant(P＜0.05);The greater the diameter of the tumor, the higher the positive rate of cPLA₂ expression, and the differences are remarkably significant(P＜0.05);Conclusion ERK2 promote the occurrence and development of breast cancer by increasing the cPLA₂ expression.