Patients receiving treatment with St. John's wort or Phenytoin. Use of any herbal remedy (e.g. St. John’s wort [hypericum perforatum]) Patients must also avoid St. John’s Wort, an inducer of CYP3A4 Patients must be willing to not take St. John wort or grapefruit juice while participating in this trial and should avoid drugs that are strong inducers of P-gp, and to switch to alternative drugs when available Use of any herbal remedy (e.g. St. John’s Wort [Hypericum perforatum]) Use of any herbal remedy (e.g. St. John’s wort [Hypericum perforatum]) Use of St. John’s wort =< 7 days prior to registration Patient must not be taking Rifampin or St John`s wort. Subjects taking herbal supplements (St. John's Wort, gingko biloba, etc.) should discontinue these supplements 14 days prior to study registration. Use of regular phenytoin, carbamazepine, hypericum perforatum (also known as St. John’s wort) or rifampin Use of St. John’s wort or rifampin Use of any herbal remedy (e.g. St. John wort [Hypericum perforatum]) No concurrent herbal or unconventional therapy (e.g., St. John's wort) Use of St. John’s Wort because of its effects on hepatic drug metabolism Patient agrees to discontinue St. Johns Wort while receiving dasatinib therapy (discontinue St. Johns Wort at least 5 days before starting dasatinib) Patient is not taking St. John’s Wort Concomitant Rifampicin and St John's Wort (Warfarin may be used only with very close monitoring.) Use of any herbal remedy (e.g. St. John’s wort [Hypericum perforatum]) Concomitant treatment with rifampin and St. John’s wort Patients taking herbal remedies (e.g., St. John's Wort [Hypericum perforatum]) who cannot interrupt therapy from the time the C-13 consent is signed through 30 days after the last dose of study therapy. St. John's Wort may decrease everolimus exposure unpredictably and should be avoided. Current or recent (=< 28 days prior to randomization) use of sorivudine, brivudine, and St. John’s wort Use of any herbal remedy (e.g. St. John’s wort [Hypericum perforatum]) Patients taking herbal supplements (St. John’s Wort, gingko balboa, etc.) should discontinue these supplements two weeks prior to study registration Use of any herbal remedy (e.g. St. John’s wort [Hypericum perforatum]) Use of any herbal remedy (e.g. St. John’s wort [Hypericum perforatum]) Concomitant treatment with rifampin or St. John's Wort; patients should discontinue these drugs at least 4 weeks prior to starting protocol treatment Concomitant Medications\r\n* Patient agrees to discontinue St. Johns Wort while receiving dasatinib therapy (discontinue St. Johns Wort at least 5 days before starting dasatinib)\r\n* Patient agrees that IV bisphosphonates will be withheld for the 4 weeks of dasatinib therapy St. John’s Wort Patients taking rifampin and/or St. John's Wort No St John's wort supplement or other herbal supplementation is allowed while on trial; patients are not to take grapefruit juice during study treatment Herbal remedies (e.g., St. John's wort) within 1 week of enrollment Use of St. John’s Wort or rifampin (rifampicin) within the last 8 weeks Use of St. John’s Wort or rifampin (rifampicin) Concomitant use of St. John’s Wort or rifampin (rifampicin) Concomitant use of phenytoin, carbamazepine, rifampicin, barbiturates, or St John's Wort Use of any herbal remedy (e.g. St. John’s wort [Hypericum perforatum]) Patients must be willing to discontinue taking dong quai and/or St. John’s wort