MARCHF9, also known as membrane-associated ring-CH-type finger 9, is a RING-type E3 ubiquitin transferase. It plays significant roles in multiple biological processes. It is involved in pathways related to immune responses, cell adhesion, and membrane protein regulation [1,2,3,4,5,6,7]. Its function in ubiquitination is crucial for regulating the levels of various cell-surface membrane proteins, which has implications for overall cellular function and immune-related activities. Genetic models, such as gene knockout models, could potentially provide in-depth insights into its exact functions.

In colorectal cancer, high MARCHF9 expression is associated with advanced clinical stages, distant metastases, and poor survival outcomes. Knockdown of MARCHF9 in vitro inhibits cell proliferation and invasion, revealing its oncogenic role in this disease [1]. In lung adenocarcinoma, MARCHF9 is down-regulated in tumor tissues. Overexpression of MARCHF9 in cell lines attenuates tumor migration and invasion, suggesting it may suppress tumor progression by down-regulating ICAM-1 signaling [2].

In conclusion, MARCHF9 has diverse functions in regulating cell-surface proteins and is involved in tumor-related processes. The study of MARCHF9 using gene knockout or knockdown models in colorectal and lung cancers has provided insights into its role in tumor progression, which may help in developing new diagnostic and therapeutic strategies for these cancers.