KIN-8194, a Src-family tyrosine kinase hematopoietic cell kinase (HCK) inhibitor, arrests growth and the integrin-mediated adhesion of BTKi-sensitive MCL cells, as well as MCL cells with primary or acquired BTKi resistance, and faces the therapeutic landscape as a promising novel treatment for MCL patients. The gene discussed is HCK; the disease is mantle cell lymphoma.