The phrase "an indispensable factor" is correct and usable in written English.
It can be used when emphasizing the essential role or importance of a particular element in a situation or process.
Example: "Effective communication is an indispensable factor in the success of any team project."
Alternatives: "a crucial element" or "a vital component."
Wang, Z. Y. et al. Axl is not an indispensable factor for Zika virus infection in mice.
The Septuagint became the instrument whereby the basic teachings of Judaism were mediated to the pagan world, and it became an indispensable factor in the spread of Christianity.
Excellent air distribution is an indispensable factor to acquire comfortable environment in high density occupant areas, such as subway stations.
Empirical experimentation on best monitoring practices on both sides show that the analog side is an indispensable factor on the quality of the sound and performance.
Today, green technology application has been the prime contributor and an indispensable factor to preserve the long term reliability of energy supply.
In short, the United Nations can be an institution that is disconnected from what matters in the lives of our citizens, or it can be an indispensable factor in advancing the interests of the people we serve.
The celebrity factor is an indispensable ingredient - a touch of glamour, of real magic.
We tested the overexpression of various combinations of the three transcription factors and PAX6, which is an indispensable gene for lacrimal glands development, in human embryonic stem cells.
Our data suggest that adiponectin serves as an indispensable cardioprotective factor against side-stream smoke exposure-induced myopathic changes possibly through facilitating autophagolysosome formation.
Non-conceptual perception is an indispensable causal factor for generation of conceptual perception, although memory, concepts and collateral information may also be required.
Activation of KROX-20 is an indispensable transcription factor for myelination and a prerequisite for Schwann cell differentiation" [250].
