The phrase 'mostly expressed' is correct in written English.
You could use it in a sentence like this: The opinion of the public was mostly expressed through social media.
TREM1 and ZNF395 expression were both mostly expressed in proximity of multilayered blood vessels of glioblastoma (Fig. 5).
The expression of BCRP was mostly expressed in the outer cells of the mammosphere [ 43].
GLP-1R is mostly expressed on beta cells, with lower levels of expression on alpha and gastric parietal cells [ 29].
CB1 receptor expression is abundant in brain while CB2 receptors are mostly expressed in hematopoietic cells.
Comparing to β III tubulin expression in neuron cytoplasm and its axons, NeuN was mostly expressed in the nuclei.
Italian lawmakers mostly expressed approval of Mr. Napolitano's plan.
But in the past year student voices have mostly expressed discontent with its policies and structure.
"And that's mostly expressed in the things we focus on, and occasionally in politics".
In European countries, crop response to ozone exposure is mostly expressed as AOT40.
Controller design for Takagi-Sugeno models are mostly expressed as LMI conditions.
"My personality has been mostly expressed through my professional ambitions," he said.
