The phrase "a pioneering factor" is correct and usable in written English.
It can be used to describe an element or aspect that plays a significant role in initiating or leading a new development or trend.
Example: "The introduction of renewable energy sources has been a pioneering factor in the fight against climate change."
Alternatives: "a groundbreaking element" or "a leading contributor".
This analysis suggests that FOXM1 might act as a pioneering factor for ERα binding in the presence of TAM and E2.
The other may reflect the differences of their activation domains: although IRF1's activation domain can potently activate transcription, our data argue that only the activation domain of IRF2 can act as a pioneering factor to prepare chromatin for rapid transcription induction in response to stimulation.
More work is needed to tease out the dynamics of RelA and PU.1 involvement in the binding of IRF5, but it is highly likely that PU.1 binds first because it functions as a pioneering factor in macrophages (Garber et al., 2012; Ghisletti et al., 2010; Heinz et al., 2010), followed by the binding of RelA at inflammatory gene loci and subsequently docking of IRF5.
Our results support the hypothesis that pioneer factors may function through different mechanisms depending on the target gene (Zaret and Carroll, 2011; Budry et al., 2012).
Cistrome and chromatin analyses revealed that HNF4G is a pioneer factor that generates and maintains enhancer landscape at gastrointestinal-lineage genes, independent of androgen-receptor signaling.
A second maternally deposited factor, Zelda (ZLD), is uniformly distributed in the embryo and is thought to act as a pioneer factor, increasing enhancer accessibility for transcription factors such as DL.
Here we utilized the MS2 live imaging system to evaluate the expression of the DL target gene short gastrulation (sog) to better understand how a pioneer factor affects the kinetic parameters of transcription.
More recently, Gata-3 has been proven to function as a pioneer factor.
It can bind to relatively closed chromatin and thus behaves as a pioneer factor in adipogenesis (Siersbaek et al., 2011).
Further, all three proteins show negative cooperativity with ETS1, a pioneer factor from the same family as PU.1.
FOXA1 has been described to function as a pioneer factor that allows the binding of ER and Androgen Receptor [ 5].
