In addition, in CRC, C5a-C5aR complement signal transduction pathway can activate the NF-κB pathway and the expression of transcription factor AP-1, which promotes the production of matrix metalloproteinases MMP-1 and MMP-9, then affects extracellular matrix decomposition and tumor progression [49, 50]. The gene discussed is C5AR1; the disease is colorectal carcinoma.