[6] NCI is the oldest and has the largest budget and research program of the 27 institutes and centers of the NIH ($6.9 billion in 2020).

[11] Antimetabolites Plant flavonoids Hormones and steroids Biologicals The NCI is divided into several divisions and centers.

Additionally, faculty at the cancer centers receive approximately 75% of the grant funding awarded by the NCI to individual investigators.

[citation needed] Lead Academic Participating Sites (LAPS) were chosen at 30 academic institutions for their ability to conduct clinical trials and screen a large number of participants and awarded grants to support the infrastructure and administration required for clinical trials.

Those passing certain thresholds are subjected to a 5 dose screen of the same 60 cell-line panel to determine a more detailed picture of the biological activity.

A second phase screen establishes the maximum tolerable dosage and involves in vivo examination of tumor regression using the hollow fiber assay.