CD99 and neoplasm: Of note, CD99 engagement increases natural killer (NK) cell-mediated tumor lysis by inducing heat shock protein 70 (HSP70) expression (Husak and Dworzak 2012) and induces tumor cell death through non-conventional mechanisms, such as methuosis (Manara et al. 2016) or the induction of oncogenic stress (Chung et al. 2017; Husak and Dworzak 2017), as described for a number of oncogenes such as RAS (Serrano et al. 1997), c-MYC (Evan et al. 1992) and BCR-ABL (Dengler et al. 2011).