NSF Division of Molecular and Cellular Biosciences: Investigator-initiated Research
NSF 21-509
https://www.nsf.gov/pubs/2021/nsf21509/nsf21509.htm?WT.mc_id=USNSF_25&WT.mc_ev=click  

The Division of Molecular and Cellular Biosciences (MCB) supports quantitative, mechanistic, predictive, and theory-driven fundamental research designed to promote understanding of complex living systems at the molecular, subcellular, and cellular levels. While recognizing the need for thorough and accurate descriptions of biological complexes and pathways, the priority of the Division is to support work that advances the field by capturing the predictive power of mechanistic, quantitative, and evolutionary approaches. 
Proposals are solicited to support research relevant to the four MCB core clusters:

• Cellular Dynamics and Function
• Genetic Mechanisms
• Molecular Biophysics
• Systems and Synthetic Biology