Generation of early, tyrphostin-sensitive CAs in MS-5 cocultures of Flt3-ITD⁺ AML blasts. Day-10 to day-14 CAs were enumerated in the cocultures of AML blasts harboring Flt3-ITDs, from patient no. 3 (A). The addition of 10 μM AG1295 (Flt3-RTK inhibitor) every 48 hours prevented the formation of early CAs, with an associated decline in nonadherent cell expansion in MS-5 stromal coculture (B).