The present disclosure provides thiazolyl-containing compounds of Formula (I), (II), or (III). The compounds described herein may be able to inhibit protein kinases (e.g., Src family kinases (e.g., hemopoietic cell kinase (HCK)), Bruton' s tyrosine kinase (BTK)) and may be useful in treating and/or preventing proliferative diseases (e.g., myelodysplasia, leukemia, lymphoma (e.g., Waldenstrom's macroglobulinemia)) and in inducing apoptosis in a cell (e.g., malignant blood cell). Also provided in the present disclosure are pharmaceutical compositions, kits, methods, and uses including or using a compound described herein.